JP2012172877A - Outside air-cooling air conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent clogging and freezing of a filter by snow in an outside air introduction circuit, and generation of vapor in an air conditioner by optimally controlling temperature/humidity in an air-conditioned room.SOLUTION: This outside air-cooling air conditioning system includes an air supply flow channel and an air return flow channel, the outside air introduction circuit, and an exhaust flow channel and a recirculation flow channel. A vaporization type humidifier and a cold water coil at a downstream side of the humidifier are disposed in the recirculation flow channel, a first bypass circuit and a first electric damper are disposed for connecting the upstream side and the downstream side of the vaporization type humidifier, a second bypass circuit and a second electric damper are disposed for connecting the downstream side of the vaporization type humidifier and the outside air introduction circuit, and a third bypass circuit and a third electric damper are disposed for connecting the upstream side of the vaporization type humidifier and the outside air introduction circuit. A snow sensor is disposed near an outside air inlet of the outside air introduction circuit. A humidification amount supplied to the air-conditioned room is controlled by the first electric damper, and the outside air introduction circuit is controlled by the second electric damper when intrusion of snow is detected by the snow sensor.

Description

  The present invention relates to an air conditioning system, and more particularly, to an air conditioning system that cools air by introducing outside air and prevents clogging of a filter due to snow and freezing / mist generation in a cold region.

  Systems that perform air conditioning by introducing outside air are widely used. However, since the temperature and humidity of the outside air fluctuate over a wide range, it is difficult to optimally control the temperature and humidity in the air-conditioned room. Especially in cold regions, there are many problems to be solved such as clogging and freezing of the filter by snow (powder snow) in the outside air introduction circuit, and generation of fog in the air conditioner.

Japanese Patent Application Laid-Open No. 2006-349276 “Air conditioner and outside air cooling operation method” includes a passage of an air supply system, a return air system, and an outside air system, and a water spray type / vaporization type / super An air conditioning system in which a water humidifier such as a sonic type is provided and a return air cooling coil is provided upstream thereof is described. However, there is no mention of low-temperature countermeasures, fog generation countermeasures, snow countermeasures, etc. in cold regions.

Japanese Patent Application Laid-Open No. 2003-148882 “Outside Air Cooling System” includes a supply air system, a return air system, and an outside air system passage, and a water spray humidifier is provided in a return flow path from the return air system. Describes a system in which the load line is set to control the humidification amount and the mixing amount of the reflux air and the outside air is controlled. However, there is no mention of low-temperature countermeasures, fog generation countermeasures, snow countermeasures, etc. in cold regions.

FIG. 12 shows a conventional general outside air introduction type air conditioning system. As its basic configuration, an air supply passage 12 and a return air passage 14 connected to the air-conditioning target room 10, an outside air introduction circuit 16 connected to the air supply passage 12 at a junction 13 on the air supply passage 12, and a return An exhaust passage 18 and a recirculation passage 20 connected to the return air passage 14 at a branch point 15 on the air passage 14 are provided, and the recirculation passage 20 is an air supply passage 12 and an outside air introduction circuit 16 at a junction 13. It is the outside air cooling air-conditioning system connected to.
FIG. 13 shows an operation method on the air diagram of the air conditioning system of FIG. The horizontal axis represents dry bulb temperature and the vertical axis represents absolute humidity.

  An object of the present invention is to provide an air conditioning system capable of optimally controlling the temperature and humidity in an air-conditioning target room, and preventing clogging or freezing of the filter due to snow in the outside air introduction circuit, generation of fog in the air conditioner, and the like. Is to provide.

In particular, the present invention is directed to an outdoor air-conditioning air conditioning system using a vaporizing humidifier (compatible with a high sensible heat load in cold regions), and its broad purpose is
1. 1. Energy saving by expanding the range of use of outside air cooling. 2. Avoiding insufficient humidification during outdoor air cooling. Compact by reducing humidification space 4. 4. Suppress fluctuations in airflow due to the operation of the electric damper with an airflow control system using an airflow sensor. 5. Reduction of air conditioner internal resistance 6. Prevention of filter clogging, freezing, and fog generation in cold regions Such as a data center in a cold region.

  The basic configuration of the present invention is that an air supply channel and a return air channel connected to an air-conditioning target room, an outside air introduction circuit connected to the air supply channel at a confluence on the air supply channel, and the return air flow Outside air having an exhaust passage and a recirculation passage connected to the return air passage at a branch point on the road, and the recirculation passage being connected to the supply passage and the outside air introduction circuit at the junction This is an air conditioning system.

As a feature of the present invention, a first bypass circuit in which a vaporizing humidifier and a cold water coil on the downstream side thereof are arranged in the recirculation flow path, and connects the upstream side and the downstream side of the vaporizing humidifier. Is provided, a first electric damper is disposed in the bypass circuit, a second bypass circuit is provided to connect the downstream side of the vaporizing humidifier and the outside air introduction circuit, and the second bypass circuit is provided in the bypass circuit. The second electric damper is disposed, a third bypass circuit is provided to connect the upstream side of the vaporizing humidifier and the outside air introduction circuit, and the third electric damper is disposed in the bypass circuit.
Further, a snow sensor (optical detector, smoke concentration meter, etc.) for detecting the presence or absence of snow (powder snow) is provided in the vicinity of the outside air inlet of the outside air introduction circuit, and the air conditioner is subject to air conditioning by the first electric damper. The humidification amount supplied into the room is controlled, and when the snow sensor detects the intrusion of snow, the outside air introduction circuit is controlled by the second electric damper.

  As a preferred aspect of the present invention, the variable air volume method is applied to the air-conditioning target room, the inverter fan or some electric dampers are controlled to vary the air flow volume, and the air volume is matched to the indoor load. Therefore, the conveyance power can be reduced.

  Further, as a preferred aspect of the present invention, a dew point sensor is provided in the air supply flow path, and the amount of humidification supplied to the air conditioned room is controlled by the first electric damper based on the dew point temperature detected by the dew point sensor. can do.

  Furthermore, as a suitable aspect of the present invention, by providing a snowfall sensor outdoors, it is possible to detect snowfall and to control the amount of outside air introduced to a minimum.

Based on such a configuration, the air-conditioning system according to the present invention can be operated as follows under conditions that allow outdoor air cooling.
1. A predetermined dew point temperature is ensured by mixing the ability of the vaporizing humidifier installed in the return air flow path with an air-cooling-compatible air conditioner with bypass air, and outside air corresponding to the humidifying ability is introduced. Outside air at a low temperature is supplied downstream of the cold water coil to reduce the pressure loss of the coil.
2. When the temperature after mixing the return air and the outside air becomes lower than the supply air temperature setting value, the air flow rate is reduced.
3. When the outside air temperature rises and the blowing temperature rises, the outside air is supplied upstream of the coil, and the deficiency is cooled by the cold water coil.

4). When outside air with extremely low temperature and humidified air are mixed, fog is generated by crossing the saturation line on the air diagram. In order to prevent this, outside air and return air are mixed to a condition where no fog is generated before mixing with humidified air to raise the temperature.
5. The filter is clogged when cold snowfall (powder snow) enters with outside air. This is preferably detected and prevented. When snowfall is detected by a snowfall sensor provided outdoors, the amount of outside air is limited, and an optical detection device (for example, a smoke concentration meter) attached to the duct detects snow intrusion. In that case, the snow is melted and discharged by bypassing the filter and mixing with the return air.
6). Since the outside air, return air, and exhaust are controlled by the electric damper, the air flow of the air conditioner fluctuates. In order to prevent this, INV (inverter) control using a wind speed (air volume) sensor and INV control using a VAV (variable air volume device) are performed.

The circuit diagram of the cooling pattern A of the air conditioning system by this invention. The circuit diagram of the cooling pattern B of the air conditioning system by this invention. The circuit diagram of the cooling pattern C of the air conditioning system by this invention. The circuit diagram of the cooling pattern D of the air conditioning system by this invention. The circuit diagram of the cooling pattern E of the air conditioning system by this invention. The circuit diagram of the cooling pattern F of the air conditioning system by this invention. The top view showing the structure of the upper part of the air-conditioning system by this invention. FIG. 8 is a horizontal sectional view taken along line AA in FIG. 7. The top view showing the structure of the lower part of the air conditioning system by this invention. FIG. 8 is a horizontal sectional view taken along line BB in FIG. 7. The air line figure showing the control method of the air-conditioning system of this invention. The circuit diagram showing the outline | summary of the conventional external air introduction type | formula air conditioning system. The air line figure showing the control method of the conventional air conditioning system. The airline diagram which simplified FIG.

First, the features of the outside air-conditioning air conditioning system using vaporizing humidification according to the present invention will be described.
(1) Utilize the capacity of the humidifier to the maximum and introduce an outside air volume that matches the capacity. Simple control can maximize the amount of cooling air from outside, making it suitable for buildings with high sensible heat loads such as data centers.
(2) The humidification amount can be proportionally controlled over a wide range.
(3) Excessive humidification can be avoided.
(4) Insufficient humidification can be avoided.

(5) The vaporization type humidifier does not require the evaporation absorption distance required by, for example, two-fluid humidification, high-pressure water spray humidification, steam humidification, etc., and the air conditioner can be made compact.
(6) By bypassing the humidifier and the cooling coil during periods when they are not needed, the resistance can be reduced and the fan power can be reduced.
(7) Freezing of the cold water coil can be prevented by bypassing the cooling coil in winter.
(8) Opening and closing the bypass damper changes the in-flight resistance. Fluctuation in the air volume due to the change in the in-machine resistance can be prevented by inverter control of the blower by the air volume sensor.

  As shown in FIG. 14, the temperature and humidity control of the air conditioning system according to the present invention can be considered by dividing the outdoor air condition into the following four zones on the air diagram. Outside air cooling can be used in Zone 1, and in Zones 2, 3, and 3 ', outside air cooling is not possible, but a minimum amount of outside air is introduced to use outside air for ventilation.

  FIG. 1 is a circuit diagram (system flow diagram) of an outside air cooling and air conditioning system according to the present invention. As a basic circuit configuration thereof, an air supply passage 12 and a return air passage 14 connected to an air-conditioning target room 10, and an air supply passage. The outside air introduction circuit 16 connected to the supply air flow path 12 at the confluence 13 on the flow path 12, the exhaust flow path 18 connected to the return air flow path 14 at the diversion point 15 on the return air flow path 14, and a part of the return air are And a flowing recirculation flow path 20.

  The recirculation flow path 20 is connected to the air supply flow path 12 and the outside air introduction circuit 16 at the junction 13. A vaporizing humidifier 22 and a cold water coil 24 on the downstream side thereof are disposed in the recirculation flow path 20, and a first bypass circuit 31 that connects the upstream side and the downstream side of the vaporizing humidifier 22 is provided. A first electric damper 32 is disposed in the bypass circuit. Moreover, the 2nd bypass circuit 33 which connects the downstream of the vaporization type humidifier 22 and the external air introduction circuit 16 is provided, and the 2nd electric damper 34 is arrange | positioned in the said bypass circuit. In addition, a third bypass circuit 35 that connects the upstream side of the vaporizing humidifier 22 and the outside air introduction circuit 16 is provided, and a third electric damper 36 is disposed in the bypass circuit. The vaporizing humidifier 22 is provided with a humidified water supply electric valve 55, and the cold water coil 24 is provided with a control electric valve 56.

  In addition, a fourth bypass circuit 37 that connects the upstream side of the cold water coil 24 and the outside air introduction circuit 16 is provided, and a fourth electric damper 38 is disposed in the bypass circuit. A fifth electric damper 40 is disposed at a position immediately before the outside air introduction circuit 16 is connected to the junction 13.

  As shown in the figure, an air flow sensor 54, an inverter fan 52, a temperature sensor 59, and a dew point sensor 58 for measuring the air flow flowing through the flow channel are mounted in the air supply flow channel 12 from the upstream side. An air flow sensor 54 and an inverter fan 53 are attached in the return air flow path 14 from the upstream side. An exhaust electric damper 26 is disposed in the exhaust passage 18. A temperature sensor 57 for detecting the temperature is attached in the air-conditioning target room 10 and is used for cascade control of the blowing temperature. Further, an air filter 50 is disposed in the recirculation flow path 20, and an air filter 51 is disposed in the outside air introduction circuit 16.

  The outside air intake passage 16 has two outside air inlets 41 and 42, and a constant air volume device (CAV) 46 is arranged at the first outside air inlet 41, and the presence or absence of snow is detected downstream thereof. A snow sensor 48, a temperature sensor 59, and a dew point sensor 58 for detection are provided. An electric damper 44 for taking in outside air is arranged at the second outside air inlet 42.

  The first electric damper 32 controls the amount of humidification supplied to the air-conditioned room 10 based on the dew point temperature detected by the dew point sensor 58, and the second electric damper 34 detects the snow intrusion by the snow sensor 48, Outside air is introduced downstream of the humidifier 22. The temperature sensor 59 and dew point sensor 58 installed in the outside air duct introduce the necessary return air volume before humidification to prevent the generation of fog.

FIG. 1 shows a circuit of the outside air cooling system when the cold water coil is unnecessary as the pattern A. FIG. 2 shows a circuit of the outside air cooling system when a cold water coil is required as the pattern B. This corresponds to the operation in zone 1 in FIG.
(1) When the dew point temperature is controlled to be constant In order to introduce the outside air corresponding to the maximum capacity of the vaporizing humidifier 22, the outside air intake electric damper 44 is controlled at the outside air dew point temperature.
When the outside air dew point temperature is high, the bypass MD (first electric damper) 32 in the first bypass circuit 31 is adjusted so that the blown air dew point temperature (DP) detected by the dew point sensor 58 is constant. Then, the amount of air passing through the vaporizing humidifier 22 is controlled, and the humidification / water supply electric valve 55 attached to the vaporizing humidifier 22 is operated to control the humidification amount.

When the maximum humidification capacity is required, the bypass MD 32 is fully closed, and control is performed so that the total return air volume passes through the humidifier 22.
When the outside air dew point temperature is high, the humidified water supply electric valve 55 is stepwise controlled and the bypass MD32 is proportionally controlled.
When humidification is unnecessary, the humidified water supply electric valve 55 is fully closed and the bypass MD32 is fully opened.

(2) When the room temperature is controlled to be constant If the room temperature is lower than the set value, the air flow rate is reduced.
After the air flow reaches the lower limit value, the air temperature setting value is controlled (cascade control) based on the room temperature detected by the room temperature sensor 57 in the air-conditioning target room 10, and the outside air amount and the return air amount are set so as to become the air temperature setting value. The mixing ratio is changed. In this method, the outside air intake electric damper 44, the exhaust electric damper 26, and the return air electric damper 30 are controlled in reverse operation.
When the outside air volume is large and the dew point temperature is lower than the set value, the outside air volume is limited (maximum outside air volume).
When the blowing temperature is higher than the set value, the fourth electric damper 38 is opened and the fifth electric damper 40 is closed, and the control electric valve 56 of the cold water coil 24 is controlled to cool.

  However, when there is a large amount of exhaust from the room, and the required minimum outside air volume becomes a large volume of air, such as when there is a large amount of pressurized air due to room pressure control or the like, there is a possibility that the humidifying capacity may be insufficient due to the outside air conditions. In such a case, it is necessary to take measures such as installing an outside air treatment facility according to the indoor conditions, directly humidifying the room, or allowing a decrease in absolute humidity and performing only temperature control.

FIG. 3 shows a circuit of the outside air cooling system when outside air cooling is impossible as pattern C. This corresponds to the operation in the zones 2, 3, 3 ′ of FIG.
1. In zone 2, the operation of humidification + cooling (outside air cooling is impossible) is performed.
(1) When the dew point temperature is controlled to be constant The bypass MD32 and the humidified water supply electric valve 55 are controlled so that the blown air dew point temperature (DP) becomes constant. The outside air is set to a necessary minimum outside air amount by a constant air volume device (CAV) 46 (electric damper 44 fully closed, electric damper 38 opened, electric damper 40 closed).
(2) When the room temperature is controlled to be constant The blower temperature set value is controlled (cascade control) according to the room temperature, and the control motor-operated valve 56 is controlled so that the blower temperature becomes the set value.

2. In zones 3 and 3 ', cooling (outside air cooling is impossible) is performed.
(1) When the dew point temperature is controlled to be constant Normally, dehumidification control is not performed, but if necessary, a dehumidification coil is added to the outside air introduction system (outside air processing unit, etc.).
(2) When the room temperature is controlled to be constant The blower temperature set value is controlled (cascade control) according to the room temperature, and the control motor-operated valve 56 is controlled so that the blower temperature becomes the set value.

Here, prevention of air volume fluctuation will be described. In-machine resistance fluctuates due to changes in the amount of outside air taken in or changes in the amount of air passing through the coil or humidifier, causing fluctuations in the air supply air volume. As a countermeasure, the following method can be considered.
1. An air volume sensor is attached to the air heating unit (AHU), and the air volume of the blower is controlled by an inverter. When a plug fan is used, the air volume is converted and controlled by the differential pressure of the fan bell mouth.
2. VAV and wind speed sensor are installed in the duct, and the fan is controlled by inverter.

FIG. 4 shows a circuit of the outside air cooling system when the snowfall sensor detects snowfall as the pattern D. FIG. 5 shows a circuit of the outside air cooling system when the snowfall sensor detects snowfall as the pattern E and the snow sensor detects snow intrusion.
As a measure against snow blowing, when snowfall is detected by a snowfall sensor (not shown) installed outdoors, the minimum outside air amount is set (the electric damper 44 is closed and the electric damper 38 is closed).
When the intrusion of snow is detected by the optical snow sensor (smoke concentration meter) 48, the snow countermeasure MD (electric damper 34) is opened and mixed with the return air without passing through the air filter 51 to melt the snow (electric damper) 38 closed, electric damper 40 closed).

FIG. 6 shows a circuit of the outside air cooling system when there is a possibility of fog generation at the mixing point of outside air and return air as the pattern F.
Considering the generation of mist, the mist is generated when the mixed line of the return-humidified air and the outside air during severe cold intersects the saturation line in the air diagram. As a countermeasure, the following method can be considered.
1. Mix the return air before humidification with cold ambient air and raise the dry bulb temperature so that it does not cross the saturation line. That is, the absolute humidity and dry bulb temperature of the outside air taken in are measured, and the fog countermeasure MD (electric damper 36) is controlled so that the dry bulb temperature at the mixing point of the outside air and the return air becomes the planned target point.
2. A brine coil is used to exchange heat between the outside air and return air in a run-around manner (however, the in-flight resistance increases).

  7 to 10 show the layout of the components of the outside air cooling and air conditioning system according to the present invention. 7 is a plan view showing the configuration of the upper part of the air conditioning system according to the present invention, FIG. 8 is a horizontal sectional view taken along line AA in FIG. 7, and FIG. 9 is a plan view showing the configuration of the lower part of the air conditioning system according to the present invention. 10 is a horizontal sectional view taken along line BB in FIG. Each component is denoted by the reference numerals shown in FIGS.

  FIG. 11 is an air line diagram showing the control method of the air conditioning system of the present invention. The horizontal axis represents dry bulb temperature and the vertical axis represents absolute humidity. The operation will be described. By adding humidification by the vaporizing humidifier to the indoor air condition 1 (for example, 25 ° C., humidity 50%), the air shifts from 1 to 3, and the air 3 and the outside air 2 that have passed through the vaporizing humidifier. The air volume ratio is controlled so that the mixing point 4 becomes a dew point temperature under indoor temperature and humidity conditions. In this invention, since the saturation efficiency of a vaporization type humidifier can be utilized effectively, humidification amount increases. It should be understood that the position of the air blowing point is closer to the saturation line compared to the conventional system of FIG.

Here, the characteristic points of the air conditioning system according to the present invention will be summarized.
1. Use a vaporizer-type humidifier and introduce the amount of outside air commensurate with its maximum humidification capacity. Proportional control that combines the step control of the bypass damper and motor-operated valve is performed in the return air flow path.
2. When it is cold outside air, the outside air is mixed downstream of the cold water coil. As a result, the amount of air passing through the coil is reduced by the amount of outside air, the pressure loss of the coil is reduced, and the fan power can be reduced.
3. Control is performed to prevent fluctuations in the air flow and room pressure of the air conditioner that occur when the outside air volume, return air volume, and exhaust volume are changed by the electric damper.

4). In order to cover a wide range of outside air temperature and humidity conditions that allow the outside air to be cooled, a small amount of return air before humidification is mixed with the outside air under conditions where fog is generated, and the mixed line of humidified return air and outside air crosses the saturation line in the air diagram. Do not. As a result, the outside air temperature and humidity conditions in which the outside air can be cooled become wide, and the outside air can be cooled even when it is cold.
5. By installing a snowfall sensor outdoors, snowfall is detected and controlled to the minimum amount of outside air. At the same time, the intrusion of snow is judged by an optical dust detector (smoke concentration meter / snow sensor) attached to the outside air duct, bypassing the outside air filter, mixing with the return air downstream of the humidifier, melting, and discharging as drain. . As a result, it is possible to perform an outside cooling operation with a minimum amount of outside air even during snowfall during cold weather.

  As described above in detail, according to the outside air-conditioning air conditioning system according to the present invention, the temperature and humidity in the air-conditioning target room are optimally controlled, and the filter is clogged or frozen due to snow in the outside air introduction circuit. An air conditioning system capable of preventing generation of fog and the like will be provided, and its technical effect is extremely remarkable.

DESCRIPTION OF SYMBOLS 10 Air-conditioning object room 12 Supply air flow path 13 Junction point 14 Return air flow path 15 Shunt point 16 Outside air introduction circuit 18 Return air flow path 20 Recirculation flow path 22 Evaporative humidifier 24 Chilled water coil 31, 33, 35, 37 Bypass circuit 26, 32, 34, 36, 38, 40, 44 Electric damper 41, 42 Outside air intake 46 Constant air volume device 48 Snow sensor 50, 51 Air filter 52, 53 Inverter fan 54 Air volume sensor 55, 56 Motorized valve 57, 59 Temperature sensor 58 Dew point sensor

Claims (4)

An air supply channel (12) and a return air channel (14) connected to the air-conditioning target room (10);
An outside air introduction circuit (16) connected to the air supply flow path at a confluence (13) on the air supply flow path;
An exhaust passage (18) and a recirculation passage (20) connected to the return air passage at a diversion point (15) on the return air passage;
The recirculation flow path is an outside air cooling air conditioning system connected to the supply air flow path and the outside air introduction circuit at the junction point,
A vaporizing humidifier (22) and a cold water coil (24) downstream thereof are disposed in the recirculation flow path,
A first bypass circuit (31) for connecting the upstream side and the downstream side of the vaporizing humidifier is provided, and the first electric damper (32) is disposed in the bypass circuit,
A second bypass circuit (33) for connecting the downstream side of the vaporizing humidifier and the outside air introduction circuit is provided, and a second electric damper (34) is disposed in the bypass circuit,
A third bypass circuit (35) for connecting the upstream side of the vaporizing humidifier and the outside air introduction circuit is provided, and a third electric damper (36) is disposed in the bypass circuit,
A snow sensor (48) for detecting the presence or absence of snow is provided near the outside air inlet of the outside air introduction circuit,
Control the amount of humidification supplied to the air-conditioned room with the first electric damper,
An outside air-conditioning air conditioning system, wherein the snow sensor detects an intrusion of snow and the outside electric introduction circuit is controlled by the second electric damper.   Applying a variable air flow method to the air-conditioned room, controlling the inverter fans (52, 53) or some electric dampers to vary the air flow and reducing the air flow to match the indoor load, thereby reducing the conveyance power. The outside air-conditioning air conditioning system according to claim 1 to be reduced.   The dew point sensor (58) is provided in the air supply flow path, and the amount of humidification supplied to the air-conditioned room is controlled by the first electric damper based on the dew point temperature detected by the dew point sensor. Outdoor air conditioning system.   The outdoor air-conditioning air conditioning system according to any one of claims 1 to 3, wherein a snowfall sensor is provided outdoors to detect snowfall and to control the amount of outside air introduced to a minimum.

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