Air conditioning system

Abstract

To provide an air conditioning system capable of achieving good responsive humidification while saving energy related to humidification of an ambient air.SOLUTION: An air conditioning system comprises: an outdoor conditioning unit 2 comprising an ambient air humidifier 2c and a cooler 2f, configured to enable performing switching among a humidification operation by the ambient air humidifier 2c, a dehumidification operation by the cooler 2f, and a dehumidification / non-dehumidification operation without humidification and dehumidification; an air conditioner 1 that adjusts the temperature of a mixed air of a return air A3 taken in from a target space S and an ambient air A0 taken in from the outdoor unit 2, and supplies the mixed air to the targe space S; and a vaporizing humidifier 13b which performs humidification of the air on the downstream side of the outdoor conditioning unit 2. The outdoor conditioning unit 2 performs the humidification operation when below a humidification upper limit value, and performs the dehumidification operation when exceeding a dehumidification lower limit value. The humidification upper limit value is set to a value lower than dehumidification lower limit value, and when the dehumidification / non-dehumidification operation is performed in the outdoor conditioning unit 2, humidification is performed by the vaporizing humidifier 13b as necessary.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air conditioning system that includes an outdoor air conditioning unit and has the function of conditioning outside air as needed and supplying it to a target space. [Background technology]

[0002] Air conditioning systems are installed in certain industrial factories, server rooms, and various other facilities to maintain the temperature and humidity of the air in a target room within a certain range throughout the year. Air conditioning systems are particularly installed for rooms that require year-round cooling to maintain the air temperature and humidity within a certain range, even when a high-load heat source is present in the room. Patent Document 1 listed below shows an example of such an air conditioning system, and describes a mechanism for circulating air between an indoor air conditioner (indoor conditioning unit) and the target space while exhausting a portion of the air in the target space (indoor-conditioned space) and taking in outside air.

[0003] When operating such an air conditioning system, the state of the outside air naturally varies depending on conditions such as the region, season, and weather at the time. Even compared to the steady-state indoor heat load and building load, the introduced outside air is a further disturbance to the indoor temperature and humidity. Therefore, such air conditioning systems are equipped with an outdoor air conditioning unit to adjust the state of the outside air (temperature and humidity), which adjusts the state of the outside air to a certain extent before introducing it into the room or into the indoor air conditioning system. The indoor air conditioning unit further conditions the mixture of the conditioned outside air and return air and supplies it to the target space.

[0004] In Japan, the absolute humidity of the outdoor air tends to be insufficient compared to indoor conditions in the dry winter, and conversely, the absolute humidity of the outdoor air tends to be excessive in the hot and humid summer. Therefore, the outdoor air is humidified in the winter and dehumidified in the summer as needed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-216330 Summary of the Invention [Problem to be solved by the invention]

[0006] In air conditioning, the required temperature and humidity conditions often have a certain range. For example, in industrial factories and server rooms, if heat sources are not removed, the indoor temperature can rise and exceed the heat resistance of the products and server integrated circuits. However, this air conditioning primarily focuses on cooling, does not generate latent heat, and condensation, which occurs due to the high humidity of the air caused by high surface temperatures, is unlikely to occur. In such cases, the required indoor air temperature and humidity ranges. Also, in industrial factories and server rooms, low humidity can cause high-voltage breakdown of products and server integrated circuits due to static electricity. This low humidity range occurs below the 40% RH threshold for human health in health-related air conditioning. Furthermore, while relative humidity can be a problem due to the nature of moisture in the air, lowering the temperature can increase the relative humidity even with the same absolute humidity. Even in such cases, the required indoor air temperature and humidity ranges remain. Therefore, for example, by changing the conditions for humidification or dehumidification and the target humidity settings for humidification or dehumidification operation depending on the season, and by setting the value for outdoor air humidity (dew point temperature or absolute humidity) as a condition for performing humidification operation lower and the target humidity setting lower when performing humidification operation in winter, and by setting the value for outdoor air humidity as a condition for performing dehumidification operation higher and the target humidity setting higher when performing dehumidification operation in summer, it is possible to save energy related to adjusting the humidity without unnecessary dehumidification or humidification when adjusting the outdoor air to the target humidity range.

[0007] In the past, various humidity-related setting values ​​were sometimes adjusted manually by an operator, such as by setting the outlet temperature and humidity of an outdoor air-conditioning unit. However, the judgment regarding the setting values ​​at that time was mainly based on the operator's experience, and when an operator lacked experience or skill, they were unable to make optimal judgments, which could result in unnecessary humidification or dehumidification.

[0008] In view of the above circumstances, the present invention aims to provide an air conditioning system that can humidify the outside air introduced into a target space by operating appropriately according to the season, thereby saving energy required for humidification. [Means for solving the problem]

[0009] The present invention provides an outdoor air conditioning unit that is configured to be able to switch between a humidifying operation using the outdoor air humidifier, a dehumidifying operation using the cooler, and a non-humidifying / non-dehumidifying operation that does not humidify or dehumidify; an air conditioner that adjusts the temperature of mixed air of return air taken in from the target space and outdoor air taken in from the outdoor air conditioning unit and supplies the mixed air to the target space; and an evaporative humidifier that humidifies air downstream of the outdoor air conditioning unit, and the humidifying operation in the outdoor air conditioning unit is performed when the dew point temperature or absolute humidity of the outdoor air taken in by the outdoor air conditioning unit is set in advance. the dehumidification operation in the outdoor air conditioning unit is performed when the dew point temperature or absolute humidity of the outdoor air taken into the outdoor air conditioning unit is above a predetermined dehumidification lower limit, and the humidification upper limit is set to a value lower than the dehumidification lower limit, the non-humidifying, non-dehumidifying operation in the outdoor air conditioning unit is performed when the dew point temperature or absolute humidity of the outdoor air taken into the outdoor air conditioning unit is above the humidification upper limit and below the humidification lower limit, and the air conditioning system is configured to perform humidification using the evaporative humidifier as necessary when at least the outdoor air conditioning unit is performing non-humidifying, non-dehumidifying operation.

[0010] In the air conditioning system of the present invention, in the outdoor air conditioning unit, the set value of the dew point temperature or absolute humidity of the outdoor air after humidification when performing humidification operation can be set to a value lower than the set value of the dew point temperature or absolute humidity of the outdoor air after dehumidification when performing dehumidification operation.

[0011] In the air conditioning system of the present invention, the outdoor air conditioning unit can further set the dew point temperature or absolute humidity of the outdoor air after humidification when performing humidification operation to the same value as the upper humidification limit value, and the outdoor air dew point temperature or absolute humidity of the outdoor air after dehumidification when performing dehumidification operation to the same value as the lower dehumidification limit value.

[0012] The air conditioning system of the present invention comprises a return air duct that guides return air from the target space to the air conditioner, and an outside air supply duct that introduces outside air into the return air duct, and the return air duct branches into a humidification duct equipped with the evaporative humidifier and a non-humidification duct that does not have a humidifier, and the air flowing through the humidification duct and the non-humidification duct is introduced into the air conditioner downstream, and the relative flow rates of the air flowing through the humidification duct and the air flowing through the non-humidification duct can be configured to be adjustable.

[0013] In addition, the air conditioning system of the present invention may be configured to include a return air duct that guides return air from the target space to the air conditioner, and an outside air supply duct that introduces outside air into the return air duct, and to include the evaporative humidifier in the return air duct.

[0014] The air conditioning system of the present invention may be configured to include, as the evaporative humidifier, an indoor humidifier that takes in indoor air of a target space, humidifies the air, and supplies the humidified air to the target space. [Effects of the Invention]

[0015] According to the air conditioning system of the present invention, the air conditioning system can achieve the excellent effect of saving energy required for humidification by appropriately operating the system according to the season in relation to humidifying the outside air introduced into the target space. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing an example (first embodiment) of a system configuration of an air conditioning system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of a water supply mechanism for a humidifier. [Figure 3] FIG. 2 is a psychrometric chart showing an example of changes in the state of air during winter operation of the air conditioning system of the first embodiment. [Figure 4] FIG. 2 is a psychrometric chart showing an example of changes in the state of air during summer operation of the air conditioning system of the first embodiment. [Figure 5] FIG. 2 is a diagram conceptually illustrating an example of the relationship between the dew point temperature and the control amount in a humidifying operation, a dehumidifying operation, and a non-humidifying / non-dehumidifying operation in an outdoor air-conditioning unit. [Figure 6] FIG. 3 is a block diagram showing another example (second embodiment) of the system configuration of an air conditioning system according to an embodiment of the present invention. [Figure 7] FIG. 10 is a psychrometric chart showing an example of changes in the state of air during winter operation of the air conditioning system of the second embodiment. [Figure 8] FIG. 3 is a block diagram showing another example (second embodiment) of the system configuration of an air conditioning system according to an embodiment of the present invention. [Figure 9] FIG. 10 is a psychrometric chart showing an example of changes in the state of air during winter operation of the air conditioning system of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0018] 1 shows an example (first embodiment) of the system configuration of an air conditioning system according to the present invention. The air conditioning system of this first embodiment includes an air conditioner 1 that supplies temperature- and humidity-adjusted air to the target space S while circulating air between the air conditioner 1 and the target space S, and an outdoor air conditioner 2 that supplies outside air, the condition of which has been adjusted as necessary, to the air circulation path between the air conditioner 1 and the target space S.

[0019] The air conditioner 1 is a typical air conditioner known as an AHU or the like, equipped with, for example, a filter, a heat exchanger that exchanges heat between circulating air and a heating or cooling medium, and a fan (the specific internal configuration of the air conditioner 1 is not directly related to the gist of the present invention, and so will not be illustrated or described in detail). The outlet side of the air conditioner 1 is connected to an air outlet 3 provided in the ceiling of the target space S by an air supply path 4. A return air outlet 5 is provided at an appropriate position in the target space S (here, on the ceiling), and the return air outlet 5 is connected to the inlet side of the air conditioner 1 by a return air path 6. In addition, an exhaust outlet 7 is provided at another position in the target space S (here, on the ceiling), and an exhaust path 8 is connected to the exhaust outlet 7, and air within the target space S is discharged from the exhaust outlet 7 through the exhaust path 8 to the outdoors as appropriate by an exhaust fan (not shown).

[0020] The outdoor air-conditioning unit 2 incorporates a filter 2a that removes dust contained in the taken-in outdoor air, a heating coil 2b as a heater that heats the outdoor air, a cooling coil 2f as a cooler that cools the outdoor air, a humidifier (outdoor air humidifier) ​​2c that humidifies the outdoor air, and a fan 2d that drives the intake and supply of outdoor air. Additionally, a preheating coil 2e is provided upstream of the outdoor air-conditioning unit 2 as a preheater that preheats the outdoor air before it passes through the heating coil 2b. The heating coil 2b, cooling coil 2f, and preheating coil 2e are, for example, general-type heat exchangers in which a heat medium flows inside a heat transfer tube equipped with fins.

[0021] The outside air taken in by the operation of fan 2d is preheated as needed by preheating coil 2e, then dust is removed by filter 2a inside outdoor air-conditioning unit 2, its temperature is adjusted as needed by heating coil 2b and cooling coil 2f, and it is further humidified as needed by outdoor air humidifier 2c before being sent downstream. The outlet side of outdoor air-conditioning unit 2 is connected to the middle of return air duct 6 via outside air supply duct 9, so that the air sent out from outdoor air-conditioning unit 2 is mixed with the air circulating in return air duct 6.

[0022] The outdoor air humidifier 2c is a steam-type humidifier that injects steam supplied from a steam generator such as a boiler (not shown) provided outside the outdoor air-conditioning unit 2 into the air flow path within the outdoor air-conditioning unit 2. A steam supply valve 10 is provided midway along the flow path that supplies steam to the outdoor air humidifier 2c, and by opening and closing the steam supply valve 10 and adjusting the opening degree, the presence or absence and amount of steam supplied to the outdoor air taken in by the outdoor air-conditioning unit 2 can be adjusted.

[0023] As described above, the cooling coil 2f is a heat exchanger composed of heat transfer tubes with fins on their surfaces. During operation, chilled water, supplied as a refrigerant from an external heat source such as a refrigerator, flows through the heat transfer tubes, exchanging heat with the air flowing outside the heat transfer tubes to cool the air. Furthermore, if the surface temperature of the heat transfer tubes and fins of the cooling coil 2f is below the dew point temperature of the air passing through the outside, moisture in the air condenses on the coil surface, which is at that surface temperature, thereby dehumidifying the air. A refrigerant supply valve 18 is provided in the flow path supplying the refrigerant to the cooling coil 2f. The amount of cooling of the outdoor air taken into the outdoor air-conditioning unit 2 is adjusted by opening and closing the refrigerant supply valve 18 and adjusting its aperture. The opening and aperture of the refrigerant supply valve 18 are controlled by the control unit 11.

[0024] In addition, dew point thermometers 19 and 12 that measure the dew point temperature of the outside air flowing through the outside air supply path 9 are provided at positions upstream of the preheating coil 2e in the outside air supply path 9 and downstream of the outside air conditioning unit 2, respectively.

[0025] The control unit 11 grasps the state of the outside air before it is taken into the air conditioning system using a dew point thermometer 19, and switches the operating state of the outdoor air conditioning unit 2 (humidifying operation or dehumidifying operation, which will be described next, or non-humidifying / non-dehumidifying operation, which will also be described later) according to the dew point temperature of the outside air grasped by the dew point thermometer 19. Furthermore, when performing these operations, the control unit 11 grasps the state of the outside air after it has passed through the outdoor air conditioning unit 2 based on the measurement value of the dew point thermometer 12, and automatically switches the steam supply valve 10 or the refrigerant supply valve 18 between open and closed states and adjusts the opening degree accordingly.

[0026] That is, during humidification operation in winter, if the absolute humidity of the outside air is significantly lower than the humidity required for the target space S, the steam supply valve 10 is opened or opened wider to supply more steam to the outside air. If the humidity is not significantly lower, the steam supply valve 10 is closed or opened narrower to reduce the amount of steam supplied to the outside air. During dehumidification operation in summer, if the absolute humidity of the outside air significantly exceeds the required humidity, the refrigerant supply valve 18 is opened or opened wider to increase the refrigerant flow rate, even though the refrigerant temperature is originally below the outside dew point. This increases the surface area of ​​the cooling coil below the dew point temperature through temperature equilibrium with the outside air, thereby strongly cooling the outside air passing through the cooling coil to a temperature below the dew point and dehumidifying it. If the absolute humidity of the outside air is not particularly high, the refrigerant supply valve 18 is closed or opened narrower to reduce the amount of cooling of the outside air. The humidification operation, dehumidification operation, and switching between them in winter and summer will be described in detail later.

[0027] In addition, the return air duct 6 has a bypass structure in which it branches into a humidifying duct 13 and a non-humidifying duct 14 downstream of the junction with the outdoor air supply duct 9, and the humidifying duct 13 and the non-humidifying duct 14 merge again to form a single return air duct 6 at a position upstream of the air conditioner 1 further downstream.

[0028] Dampers 13a and 14a are provided as flow rate adjusters for adjusting the flow rate of air flowing through the humidifying path 13 and the non-humidifying path 14. The opening degrees of the dampers 13a and 14a are controlled by a control unit 15 (note that the control unit 11 that controls the steam supply valve 10 and the control unit 15 that controls the dampers 13a and 14a may be configured as separate control devices, or may be configured as separate functions provided in the same device).

[0029] A humidifier (air-mixing humidifier) ​​13b for humidifying the air flowing through the humidification path 13 is provided at a position downstream of the damper 13a in the humidification path 13.

[0030] Air mixture humidifier 13b is an evaporative humidifier and is configured as an evaporative element provided midway along humidification path 13. As shown in Figure 2, water is pumped from a storage tank 16 provided outside humidification path 13 and dripped onto air mixture humidifier 13b, which is an evaporative element. The water that has dripped onto air mixture humidifier 13b and does not evaporate flows downward and is returned to storage tank 16. Storage tank 16 is provided with a water level gauge 16a, and when the amount of stored water becomes low, water is supplied to storage tank 16 from an external water supply source.

[0031] As shown in Figure 1, a thermo-hygrometer 17 is installed at an appropriate position within the target space S (here, near the ceiling), and as will be described later, the opening degree of dampers 13a and 14a is adjusted according to the air condition within the target space S.

[0032] The specific configuration of the flow rate adjustment unit is not limited to the damper shown here. As will be described later, any mechanism may be used as the flow rate adjustment unit as long as it is capable of adjusting the relative flow rates of the humidifying path 13 and the non-humidifying path 14. For example, it is theoretically possible to provide fans in the humidifying path 13 and the non-humidifying path 14, respectively, and adjust the rotation speed of each fan to adjust the relative flow rates. However, when implementing the present invention, if the flow rate adjustment unit is configured as a damper as exemplified here, the flow rate adjustment described below can be suitably performed with a simple configuration.

[0033] Also, although the air conditioner 1, the supply air duct 3, the return air duct 6, and other components that make up the air conditioning system are illustrated in a simplified manner, this is merely a schematic diagram. The configuration of an actual air conditioning system is usually more complex than this schematic diagram, and for example, the number of air conditioners 1, the number and shapes of the supply air ducts 3 and return air ducts 6, and the specific configuration of each component may differ from that shown in Figure 1.

[0034] Next, the operation of the first embodiment will be described.

[0035] During operation of the air conditioning system, air conditioned to an appropriate state is supplied from the air conditioner 1 to the target space S as supply air A1, and a portion of the air in the target space S (room air A2) is taken in through the return air port 5 as return air A3 and returned to the air conditioner 1 through the return air duct 6.

[0036] In addition, outdoor air A0 is taken in from the outdoor air conditioning unit 2, and the temperature and humidity are adjusted as necessary by the preheating coil 2e, heating coil 2b, cooling coil 2f, and outdoor air humidifier 2c before being supplied from the outdoor air supply path 9 to the return air path 6. In the air conditioner 1, the air taken in as return air A3 from the return air port 5 and the air (hereinafter referred to as mixed air A5) that is a mixture of the outdoor air A0 taken in from the outdoor air conditioning unit 2 are blended and supplied to the target space S as supply air A1. In addition, another portion of the indoor air A2 is discharged from the exhaust port 7 through the exhaust path 8 as exhaust air A4.

[0037] In this way, air is circulated between the air conditioner 1 and the target space S while adequate ventilation is performed by taking in part of the air as fresh outside air A0 and discharging part of the air as exhaust air A4.

[0038] In such an operation, in the case of the first embodiment, the return air passage 6 has a bypass structure constituted by the humidifying passage 13 and the non-humidifying passage 14, so that the mixed air A5 is humidified as required.

[0039] That is, the mixed air A5 flowing through the return air passage 6 flows through either the humidifying passage 13 or the non-humidifying passage 14, or both, depending on the ratio of the opening degrees of the dampers 13a, 14a provided in the humidifying passage 13 and the non-humidifying passage 14, which form a bypass structure, respectively, and at this time, the control unit 15 adjusts the opening degrees of the dampers 13a, 14a based on the state of the indoor air A2 grasped through the thermo-hygrometer 17. When it is determined that more humidity is required for the indoor air A2, the opening degree of the damper 13a is made larger relative to the opening degree of the damper 14a, allowing more mixed air A5 to flow through the humidifying passage 13, and conversely, when the humidity of the indoor air A2 is high, the opening degree of the damper 13a is made smaller relative to the opening degree of the damper 14a. A mixed air humidifier 13b is provided in the humidification path 13, while no humidifier is provided in the non-humidification path 14. Therefore, by adjusting the flow rate ratio of the air flowing through the humidification path 13 and the non-humidification path 14 in this manner, the humidity of the air (mixed air A5) before it is introduced into the air conditioner 1 can be adjusted.

[0040] Furthermore, humidity control using such a bypass structure of the humidifying path 13 and the non-humidifying path 14 makes it possible to operate with a relatively high degree of control over humidity while using an evaporative humidifier (air-mixing humidifier 13b) that consumes little energy.

[0041] Generally, evaporative humidifiers have a weakness in terms of responsiveness. Between the time when water is supplied to the element in response to a request to increase humidity and the time when the water evaporates and the humidity rises, the dripped water must be sufficiently distributed over the dry surface of the element to achieve a stable vaporized moisture balance, and the subsequent reduction due to the control of the excess supplied moisture that is difficult to evaporate must be achieved before air with the actual humidity can flow to the subsequent stage. Therefore, there is a time lag until the equilibrium is achieved before the amount of humidification can be changed (there is also a time lag between the time when the water supply to the element is stopped in response to a request to decrease humidity and the time when the water in the element has completely evaporated and the humidity has decreased). On the other hand, because humidification is achieved using the heat of the air, no additional energy is required to evaporate the water, making it an advantageous energy-efficient system. In contrast, steam humidifiers can supply moisture directly to the air in the form of water vapor, spraying the required amount of moisture which is immediately absorbed into the air, allowing for rapid humidification and rapid, stable control of the humidification amount. However, they require steam generation using a boiler or similar, which requires the use of energy from a high-temperature heat field of nearly 1,000°C from fuel combustion to generate water vapor in a low-temperature heat field of just over 100°C, resulting in poor energy cascade utilization and wasted extra energy consumption. Also, as mentioned above, while evaporative humidification is possible using the heat of the air, these systems heat the air with steam rather than using this air heat, and in circulating air conditioning systems, the air is cooled using cold water frozen in an electric refrigerator, including the amount heated by the steam, resulting in double energy usage and further waste.

[0042] In this first embodiment, an evaporative air mixture humidifier 13b is provided as a humidifier for humidifying the air mixture A5, but by adopting a bypass structure for the air mixture A5 flow path as shown in Figure 1, the shortcoming of evaporative air humidifiers, namely, their slow response, is overcome to some extent, achieving better response than when a conventional evaporative air humidifier is used. That is, water is constantly supplied to the air mixture humidifier 13b, and if it is desired to increase the humidity, the flow rate of the air mixture A5 to the humidification path 13 is increased, and the humidity immediately increases as the air mixture A5 passes through the water-containing element. If it is desired to decrease the humidity or stop the increase in humidity, the flow rate of the air mixture A5 to the humidification path 13 is reduced and the flow rate of the air mixture A5 to the non-humidification path 14 is increased, so that most of the air mixture A5 does not pass through the water-containing element, and the increase in humidity stops. With this method, although the control is somewhat less precise than when all humidification is provided by a steam humidifier, sufficient control can be achieved with an accuracy of, for example, about ±10% of the target value, and the total energy consumption related to humidification can still be kept low. Also, in the first embodiment, instead of providing all humidification by evaporative mixed air humidifier 13b alone, outdoor air A0 is humidified to a certain extent by steam outdoor air humidifier 2c, and then further humidified by evaporative mixed air humidifier 13b, so that humidification can be provided to a certain extent with good responsiveness by the steam humidifier.

[0043] The operation of the air conditioning system of the first embodiment in winter, summer and intermediate seasons will be described below.

[0044] In winter, for example, the following operation is performed: outdoor air is heated and then humidified by the outdoor air humidifier 2c provided in the outdoor air conditioning unit 2 (humidification operation). The outdoor air is heated by the preheating coil 2e and heating coil 2b, humidified by the outdoor air humidifier 2c, and then introduced into the return air path 6. The cooling coil 2f is not operated. The outdoor air is further mixed with the return air, and the humidity and temperature are adjusted by the mixed air humidifier 13b and the air conditioning unit 1 before being supplied to the target space S.

[0045] FIG. 3 shows an example of how the air condition changes during this operation. In winter, the required conditions of the indoor air A2 (indoor conditions; e.g., dry-bulb temperature 25°C ± 2°C, relative humidity 45% (absolute humidity 0.00888 kg / kg) ± 10%; the range indicated by the dashed line in the figure) are met, while the temperature and absolute humidity of the outdoor air A0 are low (outdoor conditions; dry-bulb temperature -11°C, relative humidity 70% (absolute humidity 0.00102 kg / kg); reference symbol 1 in FIG. 3). To introduce this outdoor air A0, the outdoor air A0 is first heated to a certain temperature (e.g., 5°C) by the preheating coil 2e (reference symbol 2 in FIG. 3). The outdoor air A0 heated by the preheating coil 2e is introduced into the outdoor air-conditioning unit 2 and further heated (e.g., to 14.9°C) by the heating coil 2b (reference symbol 3 in FIG. 3). Next, steam is added by the outdoor air humidifier 2c, which is a steam-type humidifier, and the air is humidified to, for example, a relative humidity of 68% (absolute humidity of 0.00718 kg / kg) (reference numeral 4 in FIG. 3). Furthermore, as the air passes through the fan 2d of the outdoor air-conditioning unit 2, it receives heat generated by the operation of the fan 2d and its temperature rises slightly (for example, to 16.0°C) (reference numeral 5 in FIG. 3).

[0046] This outdoor air A0 (with a dry-bulb temperature of 16.0°C and a relative humidity of 64%) is introduced from the outdoor air supply duct 9 into the return air duct 6, where it merges with the return air A3. Since the return air A3 is originally part of the indoor air A2, if the indoor air A2 is sufficiently conditioned, its state will be, for example, a dry-bulb temperature of 25°C and a relative humidity of 45% (absolute humidity of 0.00888 kg / kg) (see symbol 6 in Figure 3). The outdoor air A0 with a dry-bulb temperature of 16°C and a relative humidity of 64% is mixed with the return air A3 with a dry-bulb temperature of 25°C and a relative humidity of 45% to form mixed air A5. At this point, the state of the mixed air A5 will be, for example, a dry-bulb temperature of 23.2°C and a relative humidity of 48% (absolute humidity of 0.00847 kg / kg) (see symbol 7 in Figure 3).

[0047] Mixed air A5 is split into humidifying path 13 and non-humidifying path 14 and flows into each. Mixed air A5 that flows into humidifying path 13 is humidified as it passes through mixed air humidifier 13b, an evaporative humidifier. As its humidity increases, its temperature decreases as it loses heat of vaporization. The state of mixed air A5 at the outlet of mixed air humidifier 13b is, for example, a dry-bulb temperature of 17.4°C and a relative humidity of 87% (absolute humidity of 0.0108 kg / kg) (reference numeral 8 in Figure 3). The state of mixed air A5 that flows into non-humidifying path 14 is the same as its state before non-humidifying path 14 (dry-bulb temperature of 23.2°C and relative humidity of 48%; reference numeral 7 in Figure 3).

[0048] Mixed air A5, which has passed through the humidifying path 13 and is in the state indicated by reference numeral 8 in the figure, and mixed air A5, which has passed through the non-humidifying path 14 and is in the state indicated by reference numeral 6 in the figure, are mixed at the junction of the humidifying path 13 and the non-humidifying path 14. The state of mixed air A5 here is, for example, a dry-bulb temperature of 22.5°C and a relative humidity of 52% (absolute humidity of 0.00888 kg / kg) (reference numeral 9 in Figure 3).

[0049] Next, the temperature of the mixed air A5 is adjusted to the discharge temperature (e.g., 17.7°C) in the air conditioner 1, and the mixed air A1 is supplied to the target space S (reference numeral 10 in Figure 3). At this time, the humidity is adjusted to an absolute humidity of 0.00888 kg / kg as a result of the operation of the outdoor air humidifier 2c and the mixed air humidifier 13b. The supply air A1 is mixed with the room air A2, which is adjusted to an appropriate condition of a dry-bulb temperature of 25°C ± 2°C and a relative humidity of 45% ± 10% (a condition corresponding to the area indicated by reference numeral 6 and the dashed line in Figure 3).

[0050] In this type of air temperature and humidity control, the outdoor air is humidified from the absolute humidity in states indicated by symbols 1 to 3 in Figure 3 (y coordinate value in Figure 3: 0.00102 kg / kg) to the absolute humidity in state indicated by symbol 6 (0.00888 kg / kg). In a conventional method in which all outdoor air humidification is performed using a steam-type humidifier, humidification from the absolute humidity in state indicated by symbol 1 to the absolute humidity in state indicated by symbol 6 is performed using steam, and the energy required to generate the steam used for humidification is equivalent to the difference between the two values ​​(0.00786 kg / kg). However, if steam-type outdoor air humidifier 2c and evaporative mixed air humidifier 13b are used together as in the present invention, the amount of humidification by the outdoor air humidifier is limited to the difference (0.00616 kg / kg) between the absolute humidity in state 3 (0.00102 kg / kg) and the absolute humidity in state 5 (0.00718 kg / kg), and the remaining amount of humidification (the difference in the y coordinate between state 5 and state 6; 0.00170 kg / kg) is provided by mixed air humidifier 13b. This makes it possible to save energy related to humidifying the outdoor air.

[0051] In summer, for example, the following operation is performed: outdoor air is cooled and dehumidified by the cooling coil 2f of the outdoor air-conditioning unit 2 (dehumidification operation). That is, the outdoor air is cooled to a temperature below the dew point by the cooling coil 2f, and dehumidified by the water vapor condensing on the surface of the cooling coil 2f. The preheating coil 2e, heating coil 2b, outdoor air humidifier 2c, and mixed air humidifier 13b are not in operation. The cooled and dehumidified outdoor air is further mixed with the return air, and the temperature is adjusted by the air conditioner 1 as necessary before being supplied to the target space S.

[0052] FIG. 4 shows an example of how the air condition changes during this operation. In summer, the temperature and absolute humidity of outdoor air A0 are higher than the required indoor air A2 conditions (indoor conditions: e.g., dry-bulb temperature 25°C ± 2°C, relative humidity 45% (absolute humidity 0.00888 kg / kg) ± 10%; range indicated by the dashed line in the figure). (Outdoor conditions: dry-bulb temperature 31°C, relative humidity 60% (absolute humidity 0.01702 kg / kg); symbol 1 in FIG. 4). To introduce this outdoor air A0, the outdoor air A0 is first cooled to below the dew point temperature by the cooling coil 2f of the outdoor air conditioner 2. As a result, the outdoor air A0 is cooled and dehumidified to, for example, 13°C and a relative humidity of 95% (absolute humidity 0.00888 kg / kg) (symbol 2 in FIG. 3). The outside air A0 then receives heat generated by the operation of the fan 2d while passing through the fan 2d, and its temperature rises slightly (for example, to 14.1° C.) (reference numeral 3 in FIG. 4).

[0053] Outdoor air A0 in this state (dry-bulb temperature 14.1°C, relative humidity 89% (absolute humidity 0.00888 kg / kg)) is introduced from outdoor air supply path 9 into return air path 6 and merges with return air A3. Since return air A3 is originally part of indoor air A2, if indoor air A2 is sufficiently conditioned, its state will be, for example, a dry-bulb temperature of 25°C and a relative humidity of 45% (absolute humidity 0.00888 kg / kg) (reference symbol 4 in Figure 4). Outdoor air A0 with a dry-bulb temperature of 15.6°C and a relative humidity of 80% mixes with return air A3 with a dry-bulb temperature of 25°C and a relative humidity of 45% to form mixed air A5. At this point, the state of mixed air A5 will be, for example, a dry-bulb temperature of 22.8°C and a relative humidity of 51.4% (absolute humidity 0.00888 kg / kg) (reference symbol 5 in Figure 4).

[0054] When humidification by the mixed air humidifier 13b is not performed, the entire mixed air A5 passes through the non-humidification path 14 and enters the air conditioner 1 in the above-described state (the state indicated by reference numeral 5 in FIG. 4). There, its temperature is adjusted to the discharge temperature (e.g., 15.3°C) and supplied to the target space S as supply air A1 (reference numeral 6 in FIG. 4). At this time, the humidity is pre-adjusted to approximately 0.00888 kg / kg absolute humidity by the action of the cooling coil 2f in the outdoor air conditioner 2 described above. The supply air A1 is mixed with the room air A2, which is adjusted to an appropriate state of a dry-bulb temperature of 25°C ± 2°C and a relative humidity of 45% (absolute humidity of 0.00888 kg / kg) ± 10% (the state corresponding to the area indicated by reference numeral 4 and the dashed line in FIG. 4).

[0055] During the intermediate seasons when no strong heating / humidification, cooling / dehumidification is required for the outdoor air, the following operation is performed, for example: In the outdoor air-conditioning unit 2, the heating coil 2b, cooling coil 2f, and humidifier 2c are not operated, and only the fan 2d is operated to perform air-blowing operation. The preheating coil 2e is also not operated. (This operating state in which the outdoor air-conditioning unit 2 does not humidify or dehumidify the outdoor air is hereinafter referred to as "non-humidifying / non-dehumidifying operation." The state in which the outdoor air-conditioning unit 2 only blows air corresponds to "non-humidifying / non-dehumidifying operation.") If necessary, the temperature and humidity of the air are adjusted by the air conditioner 1 and the mixed air humidifier 13b.

[0056] For example, when the temperature and absolute humidity of the outdoor air are slightly lower than the required indoor conditions, the outdoor processing unit 2 only blows air, while the air conditioner 1 and the mixed air humidifier 13b adjust the temperature and humidity. Although a separate explanation using a new psychrometric chart will not be given for such an operation, for example, in the psychrometric chart shown in Figure 3, outdoor air A0 in a state corresponding to or near reference number 4 is mixed with return air A3, humidified by the mixed air humidifier 13b, and cooled by the air conditioner 1 (corresponding to reference numbers 7 to 10 in Figure 3), and then supplied to the target space S as supply air A1.

[0057] Also, for example, if the outdoor air temperature is slightly higher than the required indoor conditions, but the absolute humidity is within an acceptable range, the air A5 is a mixture of outdoor air A0 taken in from the outdoor air conditioning unit 2 in fan operation and return air A3, and the air that has only been cooled by the air conditioner 1 is supplied to the target space S as supply air A1.

[0058] The control unit 11 automatically switches between the above-described operating modes (humidification operation, dehumidification operation, and non-humidifying / non-dehumidifying operation) based on the dew-point temperature (or absolute humidity) of the outdoor air before it is taken into the outdoor air-conditioning unit 2. In this first embodiment, the dew-point temperature is measured by a dew-point thermometer 19 located upstream of the preheating coil 2e in the outdoor air supply path 9. That is, the control unit 11 controls the outdoor air-conditioning unit 2 to perform a humidification operation when the outdoor air dew-point temperature (or the corresponding absolute humidity) is significantly lower than the humidity range acceptable for the indoor conditions, and controls the outdoor air-conditioning unit 2 to perform a dehumidification operation when the absolute humidity is higher than the humidity range acceptable for the indoor conditions. Furthermore, when the absolute humidity is within the acceptable range (i.e., within the humidity range acceptable for the indoor conditions or slightly lower than the humidity range acceptable for the indoor conditions), the outdoor air-conditioning unit 2 performs a non-humidifying / non-dehumidifying operation. At this time, if necessary, humidity is adjusted by appropriately humidifying the air using the air-mixing humidifier 13b downstream of the outdoor air-conditioning unit 2. The humidification by the mixed air humidifier 13b is controlled by the control unit 15.

[0059] Here, in the case of this first embodiment, the dew point temperature used as a condition for switching the operating state of the outdoor air conditioning unit 2 as described above is a different value when performing dehumidification operation and when performing humidification operation, and also the dew point temperature set as the target value in each operating state is a different value when performing dehumidification operation and when performing humidification operation.

[0060] FIG. 5 is a graph conceptually illustrating an example of dew-point temperature control in the outdoor air conditioning unit 2. For example, in an air conditioning system such as the first embodiment, the lower limit of the outdoor air dew-point temperature (dehumidification lower limit) for the dehumidification operation of the outdoor air conditioning unit 2 is set to 12°C in advance. When the dew-point temperature of the outdoor air A0 (inlet measurement value) as determined through the measurement value of the dew-point thermometer 19 exceeds 12°C, dehumidification operation is performed using the cooling coil 2f. In this case, the target value (set value) of the dew-point temperature of the outdoor air A0 measured by the dew-point thermometer 12 downstream of the outdoor air conditioning unit 2 is set to 12°C, the same as the dehumidification lower limit, and proportional control is performed so that the dew-point temperature of the outdoor air A0 on the outlet side of the outdoor air conditioning unit 2 measured by the dew-point thermometer 12 (outlet measurement value) approaches the set value of 12°C. The control unit 11 adjusts the aperture of the refrigerant supply valve 18 depending on the difference between the outlet measurement value and the set value. The gradient line for dehumidification operation in Figure 5 shows a proportional band between a set temperature of 100% and a set temperature of 12°C at 0%. For example, if the proportional band is taken with a 100% setting of 20°C dew point temperature, then proportional control will be performed with a difference of 8°C.

[0061] For the humidification operation of the outdoor air conditioning unit 2, the upper limit of the outdoor air dew point temperature (the humidification upper limit) is set lower than the dehumidification lower limit (e.g., 9°C). When the inlet measurement value falls below 9°C, the outdoor air A0 is heated using the heating coil 2b (and, if necessary, the preheating coil 2e), while the outdoor air A0 is humidified using the outdoor air humidifier 2c. At this time, the dew point temperature set value of the dew point thermometer 12 is set to 9°C, the same as the humidification upper limit, and the control unit 11 performs proportional control so that the outlet dew point temperature measured by the dew point thermometer 12 approaches the set dew point temperature of 9°C. The control unit 11 adjusts the opening of the steam supply valve 10 according to the difference between the outlet measurement value and the set value. The sloped line for the humidification operation in Figure 5 represents a proportional band between a set temperature of 100% and a set temperature of 9°C. For example, if the proportional band is taken with a 100% setting of a dew point temperature of -3°C, proportional control is performed with a difference of 12°C. On the downstream side of the outside air supply passage 9, humidification by the air mixing humidifier 13b and temperature adjustment by the air conditioner 1 are further performed as necessary.

[0062] When the inlet measurement value is above the upper humidification limit (9°C) and below the lower dehumidification limit (12°C), the outdoor air-conditioning unit 2 does not humidify or dehumidify, and only blows air using the fan 2d (non-humidifying, non-dehumidifying operation). At this time, if necessary, the taken-in outdoor air A0 (more precisely, the mixed air A5 mixed with the outdoor air A0) is humidified by the mixed air humidifier 13b, or the temperature is adjusted by the air conditioner 1.

[0063] Although the above description has been given of the case where the conditions for each operation are determined based on the dew point temperature, the same control is possible using absolute humidity instead of the dew point temperature.

[0064] In this way, controlling the dew point so that its target value (set value) changes depending on the operating state is advantageous in terms of energy conservation. The required temperature and humidity conditions for air conditioning can be extremely strict depending on the type and use of the space being controlled, but in many cases there is a certain range, as shown by the dashed lines in Figures 3 and 4. In such cases, it is not necessary to match the target dew point temperature (or absolute humidity) values ​​for humidification and dehumidification (i.e., to always maintain the air in exactly the same state). Setting the indoor dew point temperature higher when the outdoor dew point temperature is high, and setting the indoor dew point temperature lower when the outdoor dew point temperature is low, can reduce energy consumption while maintaining indoor humidity within an appropriate range without unnecessary humidification or dehumidification. For example, as shown by the dashed line in Figure 5, if the upper humidification limit is set equal to the lower dehumidification limit (i.e., the same 12°C dew point temperature is set as the reference temperature for humidification or dehumidification, and dehumidification is performed when the outdoor dew point is above 12°C and humidification is performed when it is below 12°C), and the dew point temperature setting on the outlet side of the outdoor air conditioner is also set to the same value, when the outdoor dew point is around 12°C, frequent switching between dehumidification and humidification may result in excessive load on the system, and in humidification, unnecessary humidification will be performed by the difference between the control conditions shown by the solid line and the control conditions shown by the dashed line. Control such as that of the first embodiment shown by the solid line can reduce the energy consumed by such unnecessary humidification.

[0065] Furthermore, in the case of the first embodiment, when humidifying operation or non-humidifying, non-dehumidifying operation is performed, the mixed air A5 is humidified as needed by the evaporative mixed air humidifier 13b provided downstream of the outdoor air-conditioning unit 2. In this way, as described above, during humidifying operation, the energy required for humidification can be reduced by using the evaporative mixed air humidifier 13b to provide a portion of the humidification amount for the outdoor air A0. Furthermore, when a small amount of humidification is performed during non-humidifying, non-dehumidifying operation, the entire amount of humidification is provided by the evaporative mixed air humidifier 13b. In particular, during the intermediate seasons when non-humidifying, non-dehumidifying operation is frequently performed, ideally all humidification would be performed by the evaporative mixed air humidifier 13b, and a significant energy saving effect can be expected regarding humidification. While the above description is based on an example in which humidification is performed by the mixed air humidifier 13b as needed during both humidification and non-humidifying / non-dehumidifying operation, it is also possible to configure the mixed air humidifier 13b to perform humidification only during non-humidifying / non-dehumidifying operation. Alternatively, if the absolute humidity of the outdoor air A0 dehumidified by the outdoor air-conditioning unit 2 is insufficient for some reason during dehumidification operation, the mixed air humidifier 13b may be used downstream to fine-tune the humidity. However, if it is desired to minimize the energy required for humidification, it is of course more effective for energy conservation to configure the mixed air humidifier 13b to perform humidification as needed during both humidifying and non-humidifying / non-dehumidifying operation, and to minimize humidification by the mixed air humidifier 13b during dehumidifying operation of the outdoor air-conditioning unit 2.

[0066] In the past, the dew-point temperature setting (see FIG. 5 ) during air conditioning system operation was sometimes manually adjusted by an operator. However, the operator's experience was largely responsible for determining the appropriate dew-point temperature setting and the appropriate dew-point temperature for humidification and dehumidification (the upper and lower humidification limits). This often resulted in inefficient humidification and dehumidification, leading to energy waste. As in the first embodiment, the dew-point temperature (or absolute humidity) used as the reference for humidification or dehumidification is set as the upper and lower humidification limits, respectively, and the upper humidification limit is set lower than the lower dehumidification limit. This allows the system to automatically and timely determine when to start humidification or dehumidification. Furthermore, by setting the target setpoint for humidification or dehumidification lower than the target setpoint for dehumidification, the system can avoid unnecessary humidification or dehumidification during humidification or dehumidification, thereby saving energy. In this case, if the set value during humidification operation is set to the same value as the humidification upper limit value and the set value during dehumidification operation is set to the same value as the dehumidification lower limit value, operation can be performed with even greater energy savings.

[0067] Figure 6 shows another example (second embodiment) of the system configuration of an air conditioning system according to the present invention. The basic configuration is the same as the first embodiment (see Figures 1 and 2), but a bypass structure is not used to humidify mixed air A5 using evaporative mixed air humidifier 13b. In this second embodiment, mixed air humidifier 13b is provided as an evaporative humidifier downstream of outdoor air-conditioning unit 2, midway along single return air path 6 through which return air A3 and mixed air A5 flow.

[0068] That is, in the second embodiment, the entire amount of mixed air A5 (outside air A0 taken in from the outdoor air-conditioning unit 2 and return air A3 taken in from the return air port) flowing through the return air passage 6 always passes through the mixed air humidifier 13b, and the presence or absence of humidification by the mixed air humidifier 13b and the amount of humidification are adjusted by adjusting the presence or absence of water supply to the mixed air humidifier 13b, which is an element, and the amount of water supplied. In the second embodiment, the control unit 15 adjusts the amount of water supplied to the mixed air humidifier 13b by adjusting the aperture of a water supply valve 20 provided in the flow path that supplies water to the mixed air humidifier 13b, thereby adjusting the amount of humidification.

[0069] Figure 7 shows an example of the changes in air quality during humidification operation in winter in an air conditioning system like the second embodiment. Outdoor air A0 (reference numeral 1 in Figure 7) with a dry-bulb temperature of -11°C and a relative humidity of 70% (absolute humidity of 0.00102 kg / kg) is preheated to approximately 5.0°C by the preheating coil 2e (reference numeral 2 in Figure 7) before being taken into the outdoor air-conditioning unit 2. The air is then further heated to approximately 14.9°C by the heating coil 2b (reference numeral 3 in Figure 7). Steam is then added by the outdoor air humidifier 2c, humidifying the air to approximately 68% relative humidity (absolute humidity of 0.00718 kg / kg) (reference numeral 4 in Figure 7). The humidified outdoor air A0 then receives heat from the fan 2d, slightly increasing its temperature (to approximately 16.0°C) (reference numeral 5 in Figure 7). The outside air A0 is then introduced into the return air duct 6 from the outside air supply duct 9 and mixed with return air A3 (reference number 6 in Figure 7) with a dry-bulb temperature of 25°C and a relative humidity of 45% (absolute humidity 0.00888 kg / kg) to become mixed air A5 (reference number 7 in Figure 7) with a dry-bulb temperature of 23.2°C and a relative humidity of 48% (absolute humidity 0.00847 kg / kg).

[0070] The process up to this point is the same as in the first embodiment (see FIG. 3), but in this second embodiment, the entire amount of mixed air A5 passes through the mixed air humidifier 13b and is humidified. After humidification, the state of mixed air A5 is, for example, a dry-bulb temperature of 22.2°C and a relative humidity of 53% (absolute humidity of 0.00888 kg / kg) (reference numeral 8 in FIG. 7).

[0071] The temperature of the mixed air A5 is further adjusted to a blowout temperature (e.g., 17.7°C) by the air conditioner 1, and the mixed air A5 is supplied to the target space S as supply air A1 (reference numeral 9 in Figure 7). The supply air A1 is mixed with the room air A2, which is adjusted to an appropriate condition of a dry-bulb temperature of 25°C ± 2°C and a relative humidity of 45% (absolute humidity 0.00888 kg / kg) ± 10% (a condition corresponding to the area indicated by reference numeral 6 and the dashed line in Figure 7).

[0072] The psychrometric chart for humidification operation in summer and other seasons is the same as that in the first embodiment (see FIG. 4), and therefore will not be described here. Also, the change in air state when humidification is performed by the air-mixing humidifier 13b while the outdoor air-conditioning unit 2 is operating in a blowing operation during the intermediate seasons roughly corresponds to the changes from reference numeral 4 onwards in FIG. 7, and therefore a detailed description of this will also be omitted.

[0073] According to the second embodiment, the responsiveness of humidification by the mixed air humidifier 13b is inferior compared to the first embodiment because the bypass structure shown in FIG. 1 is not employed. However, the operation switching control of the outdoor air-conditioning unit 2 can be performed in the same manner as in the first embodiment, and the same energy-saving effect can be achieved. That is, by using the evaporative mixed air humidifier 13b to provide the humidification amount corresponding to the difference in the y coordinate between the state indicated by reference numerals 5 and 6 in FIG. 7 (0.00170 kg / kg), it is possible to reduce the energy required for humidifying the outdoor air. Furthermore, when the outdoor air-conditioning unit 2 is operating in a non-humidifying / non-dehumidifying mode during intermittent periods, the entire amount of humidification is performed by the evaporative mixed air humidifier 13b, thereby significantly reducing the energy required for humidification.

[0074] Figure 8 shows yet another example (third embodiment) of the system configuration of an air conditioning system according to the present invention. The basic configuration is the same as the first and second embodiments (see Figures 1, 2, and 6), but in this third embodiment, instead of installing an evaporative humidifier downstream of the outdoor air-conditioning unit 2 in the return air duct 6, it is installed in an appropriate position in the target space S (for example, above the ceiling). This indoor humidifier 21 takes in a portion of the indoor air A2 from an intake port installed in the ceiling, humidifies it, and returns it to the target space S.

[0075] The indoor humidifier 21 includes an element 21a onto which water is dripped and a fan 21b that drives the circulation of air. When humidification is performed, the fan 21b is operated so that indoor air A2 in the target space S is taken into the indoor humidifier 21, passes through the element 21a, and is then supplied to the target space S. If water is simultaneously supplied to the element 21a, the water evaporates as the indoor air A2 passes through the element 21a, thereby humidifying the indoor air A2.

[0076] In the third embodiment, control unit 15 controls whether or not to humidify using indoor humidifier 21 and the amount of humidification by controlling the opening of water supply valve 21c, which is provided in the flow path that supplies water to element 21a, and the operation of fan 21b. The amount of humidification increases as more water is supplied to element 21a, and the amount of humidification also increases if the airflow rate of fan 21b is increased while water is being supplied to element 21a. In particular, when the amount of humidification is controlled by the airflow rate of fan 21b, a responsiveness similar to that of humidification control using the bypass structure in the first embodiment (see FIG. 1) can be expected.

[0077] 9 shows an example of the changes in air condition during humidification operation in winter in an air-conditioning system such as the third embodiment. Outdoor air A0 (reference numeral 1 in FIG. 9) with a dry-bulb temperature of -11°C and a relative humidity of 70% (absolute humidity 0.00102 kg / kg) is preheated to approximately 5.0°C by the preheating coil 2e (reference numeral 2 in FIG. 9) before being taken into the outdoor air-conditioning unit 2. The air is then further heated to approximately 14.9°C by the heating coil 2b (reference numeral 3 in FIG. 9). Steam is added by the outdoor air humidifier 2c, which humidifies the air to approximately 68% relative humidity (absolute humidity 0.00718 kg / kg) (reference numeral 4 in FIG. 9). The air then receives heat from the fan 2d, causing it to warm slightly (to approximately 16.0°C) (reference numeral 5 in FIG. 9). This outside air A0 is introduced into the return air duct 6 from the outside air supply duct 9 and mixed with return air A3 (reference number 6 in Figure 9) with a dry-bulb temperature of 25°C and a relative humidity of 45% (absolute humidity 0.00888 kg / kg) to become mixed air A5 (reference number 7 in Figure 9) with a dry-bulb temperature of 23.2°C and a relative humidity of 48% (absolute humidity 0.00847 kg / kg).

[0078] The process up to this point is the same as in the first and second embodiments (see Figures 3 and 7), but in this third embodiment, the mixed air A5 is not humidified by an evaporative humidifier, and a portion of the indoor air A2 is humidified by the indoor humidifier 21.

[0079] The mixed air A5, which is in the state indicated by reference numeral 7 in Figure 9, is introduced directly into the air conditioner 1 without being humidified, and its temperature is adjusted. Specifically, it is cooled to a dry-bulb temperature of 18.7°C and a relative humidity of 63% (absolute humidity 0.00847 kg / kg) (reference numeral 8 in Figure 9), and is supplied into the target space S as supply air A1.

[0080] Here, the humidity of the supply air A1 (absolute humidity 0.00847 kg / kg) is insufficient compared to the humidity of the indoor air A2 maintained in ideal conditions (absolute humidity 0.00888 kg / kg). To make up for this difference, a portion of the indoor air A2 in the target space S is taken into the indoor humidifier 21 and humidified. In the evaporative indoor humidifier 21, the taken-in indoor air A2 is cooled while being humidified, for example, to a dry-bulb temperature of 17.6°C and a relative humidity of 95% (absolute humidity 0.01195 kg / kg) (reference numeral 9 in FIG. 9). This air is supplied back into the target space S and mixed with the indoor air A2. Near the outlet of the indoor humidifier 21, the state of the indoor air A2 mixed with the humidified air is, for example, a dry-bulb temperature of 18.8°C and a relative humidity of 66% (absolute humidity 0.00888 kg / kg) (reference numeral 10 in FIG. 9). In this way, the entire indoor air A2 is maintained at an average dry-bulb temperature of 25°C ± 2°C and a relative humidity of 45% (absolute humidity 0.00888 kg / kg) ± 10% (a state corresponding to the area indicated by symbol 6 and dashed line in Figure 9).

[0081] The psychrometric chart for humidification operation in summer and the like is the same in this third embodiment as in the first embodiment (see FIG. 4), and therefore will not be described here. Also, during the intermediate seasons, it is expected that humidification will be performed by the indoor humidifier 21 while the outdoor air-conditioning unit 2 is operating in a blowing operation, and the change in the state of the air at this time will generally correspond to the changes from reference numeral 4 onwards in FIG. 9, and therefore a detailed description of this will also be omitted.

[0082] Even with an embodiment like this third embodiment, the same energy-saving effect can be achieved by controlling the switching of the operation of the outdoor air-conditioning unit 2 as in the first and second embodiments. Furthermore, if the amount of humidification is adjusted by operating the fan 21b during humidification by the indoor humidifier 21, the same responsiveness as in the first embodiment can be achieved with respect to humidification by the evaporative humidifier.

[0083] As described above, the air conditioning system of each of the above embodiments includes a steam-type outdoor air humidifier 2c that humidifies the outdoor air A0 introduced into the target space S, and a cooler (cooling coil) 2f that cools the outdoor air A0, and is configured to be able to switch between a humidification operation by the outdoor air humidifier 2c, a dehumidification operation by the cooler 2f, and a non-humidification / non-dehumidification operation that does not humidify or dehumidify; an air conditioner 1 that adjusts the temperature of mixed air of return air A3 taken in from the target space S and outdoor air A0 taken in from the outdoor air conditioner 2 and supplies the mixed air to the target space S; and an evaporative humidifier (mixed air humidifier 13b, indoor humidifier 21) that humidifies the air downstream of the outdoor air conditioner 2, and the humidification operation in the outdoor air conditioner 2 is performed by switching between the outdoor air humidifier 2c, the dehumidification operation by the cooler 2f, and a non-humidification / non-dehumidification operation that does not humidify or dehumidify. The outdoor air conditioning unit 2 is configured to perform a dehumidification operation when the dew-point temperature or absolute humidity of the outdoor air A0 taken into the outdoor air conditioning unit 2 is below a preset upper limit for humidification. The dehumidification operation in the outdoor air conditioning unit 2 is performed when the dew-point temperature or absolute humidity of the outdoor air A0 taken into the outdoor air conditioning unit 2 is above a preset lower limit for dehumidification, the upper limit for humidification being set to a value lower than the lower limit for dehumidification. The non-humidifying, non-dehumidifying operation in the outdoor air conditioning unit 2 is performed when the dew-point temperature or absolute humidity of the outdoor air A0 taken into the outdoor air conditioning unit 2 is above the upper limit for humidification and below the lower limit for humidification. When performing a non-humidifying, non-dehumidifying operation in at least the outdoor air conditioning unit 2, humidification is performed as needed using an evaporative humidifier (air-mixing humidifier 13b, indoor humidifier 21). This configuration allows the timing for starting the humidifying or dehumidifying operation to be automatically and timely determined. Furthermore, since humidification is performed using an evaporative humidifier at least during non-humidifying, non-dehumidifying operation of the outdoor air conditioning unit 2, energy required for humidification can be saved.

[0084] Furthermore, in the air conditioning system of each embodiment, the set value of the dew point temperature or absolute humidity of the humidified outdoor air A0 when performing humidification operation in the outdoor air conditioning unit 2 can be set to a value lower than the set value of the dew point temperature or absolute humidity of the dehumidified outdoor air A0 when performing dehumidification operation. In this way, unnecessary humidification or dehumidification is not performed when performing humidification or dehumidification operation, and energy-saving operation can be performed.

[0085] Furthermore, in the air conditioning system of each embodiment, the outdoor air conditioning unit 2 can set the dew point temperature or absolute humidity of the humidified outdoor air A0 during humidification operation to the same value as the upper humidification limit, and the dew point temperature or absolute humidity of the dehumidified outdoor air A0 during dehumidification operation to the same value as the lower dehumidification limit. In this way, operation can be performed with even greater energy savings.

[0086] In addition, some embodiments of the air conditioning system include a return air duct 6 that guides return air A3 from the target space S to the air conditioner 1, and an outside air supply duct 9 that introduces outside air A0 into the return air duct 6. The return air duct 6 branches into a humidification duct 13 equipped with an evaporative humidifier (air-mixed humidifier) ​​13b and a non-humidification duct 14 that does not include a humidifier. Air (mixed air) A5 flowing through the humidification duct 13 and the non-humidification duct 14 is introduced downstream into the air conditioner 1, and the relative flow rates of the air (mixed air) A5 flowing through the humidification duct 13 and the non-humidification duct 14 are adjustable. By configuring the air conditioning system in this way, the above-mentioned effects can be achieved with an appropriate configuration. Furthermore, humidity can be adjusted with good response while using an evaporative humidifier.

[0087] Furthermore, the air conditioning system of some embodiments is configured to include a return air duct 6 that guides return air A3 from the target space S to the air conditioner 1, and an outside air supply duct 9 that introduces outside air A0 into the return air duct 6, and an evaporative humidifier (air-mixing humidifier) ​​13 in the return air duct 6. Even if the air conditioning system is configured in this way, the above-mentioned effects can be achieved with an appropriate configuration.

[0088] In addition, the air conditioning system of some embodiments is configured to include, as the evaporative humidifier, an indoor humidifier 21 that takes in indoor air A2 from the target space S, humidifies it, and supplies it to the target space S. Even if the air conditioning system is configured in this way, the above-mentioned effects can be achieved with an appropriate configuration.

[0089] Therefore, according to the air conditioning system of the present embodiment, the energy required for humidifying the outside air introduced into the target space can be saved by appropriately operating the system according to the season.

[0090] The air conditioning system of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0091] 1 Air conditioner 2 External conditioning machine 2c Humidifier (steam humidifier, fresh air humidifier) 2f Cooler (cooling coil) 6 Return air passage 9. Fresh air supply channel 13 Humidification path 13b Humidifiers (evaporative humidifiers, mixed gas humidifiers) 14 Non-humidified path 21 Humidifiers (evaporative humidifiers, indoor humidifiers) A0 Air (outside air) A2 Air (indoor air) A3 Air (return air) A5 Air (mixture) S target space

Claims

1. an outdoor air conditioning unit including a steam type outdoor air humidifier that humidifies outdoor air introduced into a target space and a cooler that cools the outdoor air, and configured to be able to switch between a humidifying operation using the outdoor air humidifier, a dehumidifying operation using the cooler, and a non-humidifying / non-dehumidifying operation that does not humidify or dehumidify; an air conditioner that adjusts the temperature of mixed air of return air taken in from the target space and outside air taken in from the outside air conditioner and supplies the mixed air to the target space; an evaporative humidifier that humidifies air downstream of the outdoor air-conditioning unit; Equipped with The humidification operation in the outdoor air-conditioning unit is performed when a dew point temperature or absolute humidity of the outdoor air taken into the outdoor air-conditioning unit is lower than a preset humidification upper limit value, The dehumidification operation in the outdoor air-conditioning unit is performed when the dew point temperature or absolute humidity of the outdoor air taken into the outdoor air-conditioning unit exceeds a predetermined dehumidification lower limit value, The humidification upper limit is set to a value lower than the dehumidification lower limit, The non-humidifying and non-dehumidifying operation in the outdoor air-conditioning unit is performed when the dew-point temperature or absolute humidity of the outdoor air taken into the outdoor air-conditioning unit is equal to or higher than the humidification upper limit value and equal to or lower than the humidification lower limit value, When at least the outdoor air-conditioning unit is operating in a non-humidifying and non-dehumidifying mode, the evaporative humidifier is configured to humidify as needed. An air conditioning system characterized by:

2. In the outdoor air-conditioning unit, When performing humidification operation, the dew point temperature or absolute humidity setting for the outside air after humidification is: When performing dehumidification operation, the temperature must be set lower than the dew point temperature or absolute humidity of the outside air after dehumidification.

2. The air conditioning system according to claim 1,

3. In the outdoor air-conditioning unit, The set value of the dew point temperature or absolute humidity of the outside air after humidification when performing the humidification operation is set to the same value as the humidification upper limit value, When performing dehumidification operation, the dew point temperature or absolute humidity of the outside air after dehumidification must be set to the same value as the above-mentioned lower limit value.

3. The air conditioning system according to claim 2, wherein:

4. A return air duct that guides return air from the target space to the air conditioner; an outside air supply path that introduces outside air into the return air path; Equipped with The return air duct is a humidification path provided with the evaporative humidifier; It branches into a non-humidified path without a humidifier, The air flowing through the humidifying path and the non-humidifying path is introduced into the air conditioner at the downstream side, The relative flow rates of the air flowing through the humidifying passage and the air flowing through the non-humidifying passage are adjustable. The air conditioning system according to any one of claims 1 to 3,

5. A return air duct that guides return air from the target space to the air conditioner; an outside air supply path that introduces outside air into the return air path; Equipped with The return air duct is provided with the evaporative humidifier. The air conditioning system according to any one of claims 1 to 3,

6. The evaporative humidifier is an indoor humidifier that takes in indoor air from the target space, humidifies it, and supplies it to the target space. The air conditioning system according to any one of claims 1 to 3,

Images