JP5451566B2 - Air conditioning control device, air conditioning control system, and air conditioning control method - Google Patents

Description

  The present invention relates to an air conditioning control device and an air conditioning control method for controlling an air conditioning control system.

  2. Description of the Related Art Conventionally, an air conditioning system that uses a VAV (Variable Air Volume) unit (hereinafter referred to as a variable air volume unit) that variably controls the air volume in a controlled area has been proposed (see, for example, Patent Document 1). An example of such an air conditioning system is shown in FIG.

The air conditioning system shown in FIG. 3 mixes the outside air taken in from the outside and a part of the exhaust to generate conditioned air (supply air), and the supply air supplied from the air conditioner 1 changes the amount of air flow. Controlled areas 2-1 to 2-3 supplied by the units 45-1 to 45-3, the control device 3 for controlling the operation of the air conditioner 1, and a plurality of controlled areas provided in the exhaust duct 51, respectively. and a sensor 4 for measuring the CO ₂ concentration of the exhaust gas discharged from 2-1 to 2-3.

  The air conditioner 1 includes an air filter 11 that removes dust from the outside air taken in via the outside air duct 41 and the outside air damper 42, and a cooling coil that cools outside air that is supplied with cold water through the motor-operated valve 12 and passes through the air filter 11. 13 and a heating coil 15 for heating the outside air that has been supplied with hot water via the motor-operated valve 14 and passed through the air filter 11, a fan 16 a and an inverter 16 b, and is cooled or heated by the cooling coil 13 or the heating coil 15. The air supply blower 16 sends out outside air (hereinafter referred to as air supply) to the air supply duct 43. A part of the exhaust gas is returned to the air conditioner 1 as return air via the return air adjustment damper 54.

  The air supplied from the air conditioner 1 to the air supply duct 43 is provided in each of the branch ducts 44-1 to 44-3 and the branch ducts 44-1 to 44-3 branched from the air supply duct 43. Are supplied to the controlled areas 2-1 to 2-3 via the variable air volume units 45-1 to 45-3. Exhaust gas from the controlled areas 2-1 to 2-3 is taken into the exhaust duct 51 and is discharged to the outside through the exhaust damper 53 by the exhaust fan 52 including the fan 52a and the inverter 52b.

  The control device 3 includes a motor-operated valve 12, a cooling coil 13, a motor-operated valve 14, a heating coil 15, an air supply blower 16, an outside air damper 42, variable air volume units 45-1 to 45-3, an exhaust air blower 52, an outside air damper 53, and a return. The air conditioning damper 54 is connected to a room temperature sensor (not shown) installed in each of the air supply temperature sensor 46, the exhaust temperature sensor 55, and the controlled areas 2-1 to 2-3. As a result, the control device 3 uses the supply air temperature, exhaust temperature, and room temperature acquired from the supply air temperature sensor 46, the exhaust temperature sensor 55, and the room temperature sensor, the amount of outside air to be taken in (hereinafter referred to as the outside air amount), the supply air blower 16 airflows (hereinafter referred to as fan airflow), airflows sent to the controlled areas 2-1 to 2-3 by the variable airflow units 45-1 to 45-3 (hereinafter referred to as VAV airflow), and airflow from the air conditioner 1. The target value of the supply air temperature is calculated, and based on this target value, the motor-operated valve 12, the cooling coil 13, the motor-operated valve 14, the heating coil 15, the air supply blower 16, the outside air damper 42, and the variable air volume units 45-1 to 45-45. −3, by controlling the operation of the exhaust blower 52, the outside air damper 53, and the return air adjusting damper 54, the air conditioning of the controlled areas 2-1 to 2-3 is controlled.

JP-A-8-271027

  In the air conditioning control system as described above, in order to maintain the air quality, the minimum air volume is normally set as the VAV air volume so that the air in the controlled area is replaced with the supply air and ventilated. This minimum air volume is set as a fixed value assuming that the occupant density is high and the air quality is poor, such as 40% of the rated air volume preset in the variable air volume units 45-1 to 45-3. . Therefore, the control range of the VAV air volume is limited to a range equal to or greater than the minimum air volume. For example, if the minimum air volume of the VAV air volume is 40% of the rated air volume, the control range of the VAV air volume is a range of 40 to 100% of the rated air volume.

  For this reason, for example, the indoor load of the controlled area 2-1 of the controlled areas 2-1 to 2-3 is reduced, and the VAV air volume is less than 40% of the rated air volume, and the indoor load can be covered. Even if the air quality is low and the air quality is good, the VAV air volume cannot be lowered below 40% of the rated air volume, which is the fixed minimum air volume. Then, in controlled area 2-1, since there is too much air volume, room temperature will fall too much. In such a case, conventionally, an excessive decrease in the room temperature of the controlled area 2-1 was prevented by performing an air supply temperature reset control for increasing the air supply temperature.

  However, if the supply air temperature is raised by the supply air temperature reset control, the air flow for the controlled areas 2-2 and 2-3 in which the indoor environment is good increases, so that the fan air flow also increases. The energy consumption was increasing.

  Accordingly, an object of the present invention is to provide an air conditioning control device, an air conditioning system, and an air conditioning control method that can prevent an increase in energy consumption.

In order to solve the above-described problems, an air conditioning control device according to the present invention is provided in an exhaust duct, and includes a sensor for measuring the CO ₂ concentration of exhaust exhausted from a plurality of controlled areas, and the outside. A variable air volume unit in an air conditioning system comprising an air conditioner that mixes outside air and a part of exhaust gas to generate conditioned air, and a variable air volume unit that supplies conditioned air supplied from the air conditioner to each controlled area. Is a control device for controlling the air volume of the exhaust air, and calculates a necessary outside air amount that is the amount of the outside air mixed with the conditioned air generated in the air conditioner based on the CO ₂ concentration of the exhaust discharged from the plurality of control areas. The outside air amount calculating means, the design outside air amount preset for the controlled area, and the reduction ratio of the required outside air amount calculated by the outside air amount calculating means are preset in the variable air volume unit. The minimum air volume calculating means for calculating the minimum air volume of the variable air volume unit in which the air quality is matched by multiplying the initial set minimum air volume value, and the variable air volume unit preset from the minimum air volume calculated by the minimum air volume calculating means. And a control means for controlling the air volume of the variable air volume unit within a range up to the maximum air volume.

  In the air conditioning control device, the minimum air volume calculating means includes a first computing means for obtaining a ratio of a difference between the design outside air volume and the required outside air volume with respect to the rated air volume of the air conditioner, and an initial setting minimum air volume of the variable air volume unit. You may make it provide the 2nd calculating means which calculates the minimum air volume according to the state of the air quality of a variable air volume unit by multiplying a value.

In addition, an air conditioning control system according to the present invention mixes a sensor for measuring the CO ₂ concentration of exhaust exhausted from a plurality of controlled areas, outside air taken in from the outside, and part of the exhaust, provided in the exhaust duct. An air conditioner that generates conditioned air, a variable air volume unit that supplies conditioned air supplied from the air conditioner to each controlled area, and a control device that controls the air volume of the variable air volume unit. Is the air conditioning control device described above.

In addition, the air conditioning control method according to the present invention mixes a sensor that is provided in an exhaust duct and measures the CO ₂ concentration of exhaust exhausted from a plurality of controlled areas, outside air taken in from the outside, and part of the exhaust. A control method for an air conditioning system comprising an air conditioner that generates conditioned air and a variable air volume unit that supplies conditioned air supplied from the air conditioner to each controlled area. An outside air amount calculating step for calculating a required outside air amount that is the amount of outside air mixed with the conditioned air generated in the air conditioner based on the CO ₂ concentration of the exhaust gas, and a design preset for the controlled area Multiplying the reduction ratio between the outside air volume and the required outside air volume calculated in the outside air volume calculation step by the initial minimum air volume value preset in the variable air volume unit, the variable air volume unit that matches the air quality condition A minimum air volume calculating step for calculating the minimum air volume of the knit, and a control step for controlling the air volume of the variable air volume unit within a range from the minimum air volume calculated by the minimum air volume calculating step to the maximum air volume preset in the variable air volume unit. It is characterized by having.

According to the present invention, based on the CO ₂ concentration of exhaust discharged from a plurality of control areas, a required outside air amount that is the amount of outside air mixed with conditioned air generated in an air conditioner is calculated, and Multiply the design air volume set in advance and the calculated reduction ratio of the required outside air by the initial minimum air volume value preset in the air volume unit and adjust the air volume unit according to the air quality. By calculating the minimum air volume and controlling the air volume of the variable air volume unit within the range from the calculated minimum air volume to the maximum air volume preset in the variable air volume unit, the minimum air volume can be further reduced. It becomes possible to widen the control range of the air volume of the air supply. Thereby, it is possible to prevent the controlled area from being overcooled and the increase in the supply air temperature due to the supply air temperature reset control, thereby preventing an increase in energy consumption.

(A) The figure which shows the structure of the air conditioning system which concerns on this invention, (b) The figure which shows the structure of a control apparatus. It is a flowchart which shows operation | movement of a control apparatus. It is a figure which shows the structure of the conventional air conditioning system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, components equivalent to those of the air conditioning control system described in the background art section with reference to FIG. 3 are denoted by the same names and reference numerals, and description thereof is omitted as appropriate.

[Configuration of air conditioning system]
As shown to Fig.1 (a), the air conditioning system which concerns on this Embodiment mixes the external air taken in from the outside, and a part of exhaust, and produces | generates conditioned air, and this air conditioner 1 Controlled areas 2-1 to 2-3 in which the conditioned air supplied is supplied by the variable air volume units 45-1 to 45-3, the control device 3 that controls the operation of the air conditioner 1, and the exhaust duct 51, respectively. And a sensor 4 that measures the CO ₂ concentration of the exhaust discharged from the plurality of controlled areas 2-1 to 2-3.

<Configuration of control device 3>
The control device 3 includes a motor-operated valve 12, a cooling coil 13, a motor-operated valve 14, a heating coil 15, an air supply blower 16, an outside air damper 42, variable air volume units 45-1 to 45-3, an exhaust air blower 52, an outside air damper 53, and a return. The air conditioning damper 54 is connected to the CO ₂ sensor 4, the air temperature sensor 46, the exhaust gas temperature sensor 55, and room temperature sensors (not shown) installed in each of the controlled areas 2-1 to 2-3. . As a result, the control device 3 uses the supply air temperature, the exhaust temperature, and the room temperature acquired from the supply air temperature sensor 46, the exhaust temperature sensor 55, and the room temperature sensor, the amount of outside air to be taken in (hereinafter referred to as the required outside air amount), the supply air The air volume of the blower 16 (hereinafter referred to as fan air volume), the air volume sent to the controlled areas 2-1 to 2-3 by the variable air volume units 45-1 to 45-3 (hereinafter referred to as VAV air volume), and the air volume 1 The target value of the supply air temperature to be calculated is calculated, and based on this target value, the motor-operated valve 12, the cooling coil 13, the motor-operated valve 14, the heating coil 15, the air supply blower 16, the outside air damper 42, and the variable air volume unit 45-1 The air conditioning of the controlled areas 2-1 to 2-3 is controlled by controlling the operation of the exhaust fan 45-3, the outside air damper 53, the outside air damper 53, and the return air adjusting damper 54. As shown in FIG. 1B, such a control device 3 includes a VAV required air volume calculation unit 31, a required outside air volume calculation unit 32, a minimum air volume setting unit 33, a VAV air volume setting unit 34, an operation control unit 35, and a storage. At least a portion 36 is provided.

  The VAV required air volume calculation unit 31 determines the VAV air volume (hereinafter, referred to as “VAV air volume”) that requests supply to each of the controlled areas 2-1 to 2-3 based on the set temperature and room temperature of the controlled areas 2-1 to 2-3. VAV required air volume) is calculated.

The required outside air amount calculation unit 32 performs air conditioning based on the CO ₂ concentration of the exhaust gas measured by the CO ₂ sensor 4, the set value of the CO ₂ concentration, and the upper and lower limit values of the outside air amount introduced from the outside. A necessary outside air amount (necessary outside air amount) introduced from the outside by the machine 1 is calculated.

  The minimum air volume setting unit 33 uses the minimum air volume (hereinafter referred to as “the air flow rate unit 45-1 to 45-3) as a reduction ratio of the required outside air volume calculated by the required outside air volume calculation unit 32 from the design outside air volume. The minimum value of the VAV air volume of each of the variable air volume units 45-1 to 45-3 is calculated by multiplying the initial minimum air volume), and this is set as the VAV minimum air volume.

  The VAV air volume setting unit 34 is configured to control each of the controlled areas 2-1 to 2-3 based on the VAV required air volume set by the VAV required air volume calculating unit 31 and the VAV minimum air volume calculated by the minimum air volume setting unit 33. The VAV air volume of the supply air that is actually supplied is set.

  The operation control unit 35 is based on the required outside air amount calculated by the required outside air amount calculating unit 32 and the VAV air volumes of the controlled areas 2-1 to 2-3 set by the VAV required air volume setting unit 35, respectively. Motorized valve 12, cooling coil 13, motorized valve 14, heating coil 15, supply air blower 16, outside air damper 42, variable air volume units 45-1 to 45-3, exhaust air blower 52, outside air damper 53, and return air adjusting damper 54 To control the operation.

  The storage unit 36 performs various calculations, settings, and operations by the VAV required air volume calculation unit 31, the necessary outside air volume calculation unit 32, the reduction ratio calculation unit 33, the minimum air volume setting unit 33, the VAV air volume setting unit 34, and the operation control unit 35. Various information necessary for control and the like is stored.

  The control device 3 includes an arithmetic device such as a CPU, a storage device such as a memory and an HDD (Hard Disc Drive), an input device that detects input of information from outside such as a keyboard, a mouse, a pointing device, a button, and a touch panel, An I / F device that transmits and receives various information via a communication line such as the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), etc., and a CRT (Cathode Ray Tube), LCD (Liquid Crystal Display) or FED ( A computer including a display device such as a field emission display) and a program installed in the computer. That is, the hardware device and software cooperate to control the above hardware resources by a program, and the above-described VAV required air volume calculation unit 31, required outside air volume calculation unit 32, minimum air volume setting unit 33, VAV air volume setting. The unit 34, the operation control unit 35, and the storage unit 36 are realized. Note that the program may be provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, or a memory card.

<Configuration of variable air flow unit>
The variable air volume units 45-1 to 45-3 are composed of known VAV units, and the control device 3 so that the measured value of the room temperature approaches the set value of the room temperature of the controlled areas 2-1 to 2-3. The amount of VAV supply (VAV air volume) supplied to the controlled areas 2-1 to 2-3 is controlled.

<Operation of control device>
Next, operation | movement of the control apparatus 3 in the air conditioning system which concerns on this Embodiment is demonstrated with reference to FIG.

First, necessary external air amount calculation unit 32, a set value of CO ₂ concentration, and the CO ₂ concentration of the exhaust, on the basis of the lower limit on the amount of outside air introduced from the outside, the air conditioner 1 is actually introduced from the outside The amount of outside air to be used, that is, the necessary amount of outside air is calculated (step S1).

  When the required outside air volume is calculated, the minimum air volume setting unit 33 sets the ratio between the required outside air volume and the designed outside air volume to the initial set minimum VAV air volume preset in the variable air volume units 45-1 to 45-3. By multiplying, the VAV minimum air volume of each variable air volume unit 45-1 to 45-3 is set (step S2). Specifically, the VAV minimum air volume is calculated by the following equation (1). Here, the design outside air amount is the amount of outside air taken in by the air conditioner 1 set in advance in the design stage based on the size of the controlled areas 2-1 to 2-3 and the assumed personnel as design conditions. Further, the following expression (1) is applied to each of the controlled areas 2-1 to 2-3.

VAV minimum air volume = Necessary outside air volume / Design outside air volume / Rated minimum VAV air volume
... (1)
VAV minimum air volume (lower limit) <VAV minimum air volume (1) <VAV minimum air volume (maximum value)
... (2)

  The VAV minimum air volume calculated by the above equation (1) is variable from the lower limit value of the VAV air volume preset in the variable air volume units 45-1 to 45-3 to the design air volume as shown in the above equation (2). It becomes. This value is set as the VAV minimum air volume in each of the controlled areas 2-1 to 2-3. When the required outside air volume is equal to the designed outside air volume, the maximum value of the VAV minimum air volume is set as the VAV minimum air volume. The maximum value of the VAV minimum air volume is generally about 40% of the rating.

  On the other hand, the VAV required air volume calculation unit 31 controls the controlled areas 2-1 to 2 based on the set temperatures of the controlled areas 2-1 to 2-3 and the room temperatures of the controlled areas 2-1 to 2-3. -3 Each VAV required air volume is calculated (step S3). Here, the VAV required air volume calculation unit 31 obtains a set temperature from a controller or the like provided in each of the controlled areas 2-1 to 2-3, and a room temperature sensor provided in each of the controlled areas 2-1 to 2-3. Get room temperature from.

  When the VAV required air volume is calculated, the VAV air volume setting unit 34 determines the VAV of the controlled areas 2-1 to 2-3 based on the VAV required air volume and the VAV minimum air volume set by the minimum air volume setting unit 33. An air volume is set (step S4). Specifically, the VAV minimum air volume is compared with the VAV required air volume, and when the value of the VAV required air volume is equal to or greater than the value of the VAV minimum air volume, the value of the VAV required air volume is set as the VAV air volume. On the other hand, when the value of the VAV required air volume is smaller than the value of the VAV minimum air volume, the value of the VAV minimum air volume is set as the VAV air volume.

As described above, in the present embodiment, the necessary outside air amount of the air conditioner 1 based on the CO ₂ concentration of the exhaust gas is obtained, and the ratio between the necessary outside air amount and the rated outside air amount is assigned to the variable air amount units 45-1 to 45-3. Since the state monitoring VAV minimum air volume is set by multiplying the preset initial minimum VAV air volume, for example, when the CO ₂ concentration is low, such as when the number of persons existing in the controlled areas 2-1 to 2-3 is small, Since the CO ₂ concentration of the exhaust gas becomes low, the minimum air volume can be reduced to a preset lower limit value of the VAV air volume. In the conventional case as shown in FIG. 3, the minimum air volume of 40% of the rated air volume is set for the VAV air volume, and the VAV air volume can be controlled only within the range of 40% to 100% of the rated air volume. . For this reason, the room temperature is excessively lowered and the supply air temperature and the fan air volume are increased. In contrast, in the present embodiment, the minimum air volume can be made smaller than before, so that the temperature control range with the VAV air volume can be expanded. As a result, the room temperature is excessively lowered or the supply air temperature is increased. The accompanying increase in fan airflow can be prevented.

  When the minimum air volume is set, the operation control unit 35 changes the variable air volume units 45-1 to 45-45 based on the VAV air volume of the controlled areas 2-1 to 2-3 set by the VAV air volume setting unit 35. -3 is adjusted (step S5). Based on this setting, the output of the inverter of the air conditioner 1 is determined, and the fan air volume of the supply air supplied from the air conditioner 1 is determined. Thereby, the supply air according to each load is supplied to the controlled areas 2-1 to 2-3.

As described above, according to the present embodiment, in the air conditioner 1 based on the CO ₂ concentration of the exhaust discharged from the plurality of controlled areas 2-1 to 2-3 by the required outside air amount calculation unit 32. The required outside air amount that is the amount of the outside air mixed with the generated supply air is calculated, and the design outside air amount preset by the minimum air volume setting unit 33 and the necessary outside air amount calculated by the necessary outside air amount calculating unit 32 are calculated. Based on the rated air volume of the air conditioner 1 and the rated air volume of the variable air volume units 45-1 to 45-3, the minimum air volume of the variable air volume units 45-1 to 45-3 is calculated. The air volume of the variable air volume units 45-1 to 45-3 is controlled within the range from the minimum air volume calculated by the minimum air volume setting unit 33 to the maximum air volume preset in the variable air volume units 45-1 to 45-3. Since the VAV minimum air volume can be further reduced as compared with the conventional case, the control range of the VAV air volume can be widened. Thereby, since it is possible to prevent the controlled areas 2-1 to 2-3 from being overcooled and an increase in the supply air temperature due to the supply air temperature reset control, an increase in energy consumption can be prevented.

Further, in the present embodiment, since the system components set the VAV minimum air volume based on the CO ₂ concentration of the exhaust gas measured by the CO ₂ sensor used in the conventional air conditioning system shown in FIG. In addition, a sensor for measuring the CO ₂ concentration in each control area becomes unnecessary, and as a result, it can be easily introduced into an existing building and the initial cost can be suppressed.

  In the present embodiment, the case where three controlled areas 2-1 to 2-3 are provided as controlled areas for supplying air from the air conditioner 1 is described as an example, but the number of controlled areas is as follows. It is not limited to this, It can set suitably freely according to structures, such as a building.

  The present invention can be applied to various air conditioning systems that perform VAV control.

1 ... air conditioner, 2-1 to 2-3 ... the controlled area, 3 ... control unit, 4 ... CO ₂ sensor, 11 ... air filter, 12 ... electric valve, 13 ... cooling coil, 14 ... electric valve, 15 ... Heating coil, 16 ... supply air blower, 16a ... fan, 16b ... inverter, 31 ... VAV required air volume calculating unit, 32 ... required outside air volume calculating unit, 33 ... minimum air volume setting unit, 34 ... VAV air volume setting unit, 35 ... operation Control unit, 36 ... storage unit, 41 ... outside air duct, 42 ... outside air damper, 43 ... air supply duct, 44-1 to 44-3 ... branch duct, 45-1 to 45-3 ... variable air volume unit, 46 ... supply Air temperature sensor 51 ... exhaust duct 52 ... exhaust fan 52a ... fan 52b ... inverter 53 ... external air damper 54 ... return air adjustment damper 55 ... exhaust temperature sensor

Claims (4)

A sensor provided in an exhaust duct for measuring the CO ₂ concentration of exhaust exhausted from a plurality of controlled areas; an air conditioner for generating conditioned air by mixing outside air taken in from outside and part of the exhaust; A control device for controlling the air volume of the air flow rate unit in an air conditioning system including air flow rate units each supplying conditioned air supplied from the air conditioner to the controlled area,
An outside air amount calculating means for calculating a required outside air amount that is an amount of outside air mixed with the conditioned air generated in the air conditioner, based on the CO ₂ concentration of exhaust discharged from a plurality of control areas;
Multiplying the design external air amount preset for the controlled area and the required external air amount reduction ratio calculated by the external air amount calculating means by the initial set minimum air amount value preset in the variable air volume unit. Minimum air volume calculating means for calculating the minimum air volume of the variable air volume unit in which the air quality state is combined,
Control means for controlling the air volume of the variable air volume unit within a range from the minimum air volume calculated by the minimum air volume calculating means to a maximum air volume preset in the variable air volume unit. Control device. In the air-conditioning control device according to claim 1,
The minimum air volume calculating means includes
First calculating means for obtaining a ratio of a difference between the designed outside air amount and the required outside air amount with respect to a rated air amount of the air conditioner;
An air conditioning control device comprising: a second computing unit that multiplies the ratio by an initial set minimum airflow value of the variable airflow unit to calculate a minimum airflow according to the air quality state of the variable airflow unit. A sensor provided in the exhaust duct for measuring the CO ₂ concentration of the exhaust discharged from a plurality of controlled areas;
An air conditioner that mixes outside air taken in from outside and a part of the exhaust, and generates conditioned air;
A variable air volume unit that supplies conditioned air supplied from the air conditioner to each of the controlled areas;
And a control device for controlling the air volume of the variable air volume unit.
The said control apparatus is an air-conditioning control apparatus described in Claim 1 or Claim 2. The air-conditioning control system characterized by the above-mentioned. A sensor provided in an exhaust duct for measuring the CO ₂ concentration of exhaust exhausted from a plurality of controlled areas; an air conditioner for generating conditioned air by mixing outside air taken in from outside and part of the exhaust; , A control method for an air conditioning system comprising a variable air volume unit for supplying conditioned air supplied from the air conditioner to each of the controlled areas,
An outside air amount calculating step for calculating a required outside air amount that is an amount of outside air mixed with the conditioned air generated in the air conditioner based on the CO ₂ concentration of the exhaust discharged from a plurality of control areas;
Multiplying the design outside air amount preset for the controlled area and the reduction ratio of the required outside air amount calculated in the outside air amount calculating step by the initially set minimum air amount value preset in the variable air amount unit. A minimum air volume calculating step for calculating a minimum air volume of the variable air volume unit according to the air quality state;
And a control step of controlling the air volume of the variable air volume unit within a range from the minimum air volume calculated in the minimum air volume calculating step to a maximum air volume preset in the variable air volume unit. Method.

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