KR101329752B1 - Air conditioning system - Google Patents

Abstract

According to the present invention, when the operating variable value is out of the normal operating range, by shielding the injection valve, the liquid refrigerant is prevented from being injected into the compressor, so that the stability of the system can be improved.

Air conditioning system, phase separator, injection, refrigerant, valve, superheat degree, intermediate pressure

Description

[0001] Air conditioning system [0002]

The present invention relates to an air conditioning system, and more particularly, to an air conditioning system in which the performance and stability of the system can be improved.

In general, an air conditioning system is a device for cooling or heating an indoor space by performing a process of compressing, condensing, expanding, and evaporating a refrigerant.

The air conditioning system is divided into a general air conditioning system in which one indoor unit is connected to an outdoor unit, and a multi air conditioning system in which a plurality of indoor units are connected to the outdoor unit. In addition, the air conditioning system is divided into a cooling system that only operates the refrigerant cycle in one direction to supply only cool air to the room, and a cooling and heating system that can operate the refrigerant cycle in both directions to supply cold or warm air to the room.

The air conditioning system includes a compressor, a condenser, an expansion valve, and an evaporator. The refrigerant discharged from the compressor is condensed in the condenser, and then expanded in the expansion valve. The expanded refrigerant is evaporated in the evaporator, and then sucked into the compressor. During the cooling operation or the heating operation, the refrigerant is injected into the compressor to improve the performance.

However, the air conditioning system according to the related art is very difficult to control, and if the control is not properly performed, the system becomes unstable and damage to the compressor may occur.

An object of the present invention is to provide an air conditioning system in which stability and performance of a system can be improved.

The present invention passes through a condenser for condensation of a refrigerant, a first expansion device for condensing the refrigerant passing through the condenser, a second expansion device for condensing the refrigerant passing through the first expansion device, and the second expansion device. An evaporator in which one refrigerant evaporates, a refrigerant passing through the evaporator, a compressor branched and injected between the first expansion device and the second expansion device, and compressed and introduced therein, the first expansion device and the second The injection valve branched between the expansion device and the refrigerant injected into the compressor is throttled, and the first control mode for opening the injection valve, and the operation variable value of at least one operating variable is outside the preset normal operation range. In another aspect, the present invention provides an air conditioning system that switches to the first control mode and controls the second control mode to shield the injection valve.

In the present invention, the compressor includes: a first compression section in which a refrigerant that has passed through the evaporator flows and is compressed; a refrigerant that has passed through the first compression section and branched from the first expansion device and the second expansion device, And a second compression unit in which the refrigerant is introduced and compressed.

In the present invention, the operation variable includes the discharge temperature of the compressor, the inlet side temperature of the evaporator, the indoor temperature and the outdoor temperature of the air conditioning system, and the current applied to the compressor, the operation of the operating variable When at least one of the variable values is out of the normal operation range, the controller switches from the first control mode to the second control mode and controls the opening amount of the injection valve to the second control mode for a first predetermined time.

In the present invention, the number of times the operation variable value is out of the normal operation range is stored, and if the number exceeds the preset number, the second control mode is performed for a second set time longer than the first set time. do.

In the present invention, the operation variable includes the discharge temperature of the compressor, and when the discharge temperature change rate of the compressor is outside the preset discharge temperature normal change rate, the second control mode is performed for a first preset time. The number of times that the discharge temperature change rate of the compressor deviates from the discharge temperature normal change rate is stored, and when the number exceeds the predetermined number of times, the second control mode may be continued for a second set time longer than the first set time. have. The compressor may store the number of times the discharge temperature change rate of the compressor deviates from the normal discharge rate of the discharge temperature, and display a warning to the outside when the number of times exceeds the predetermined number of times.

In the present invention, the operating variable includes the temperature of the evaporator, and when the temperature change rate of the evaporator is out of a predetermined change rate of the normal evaporator temperature, the second control mode is performed for a first set time. Store the number of times the temperature change rate of the evaporator is out of the normal change rate of the evaporator temperature, and if the number exceeds the predetermined number of times, the second control mode may be continued for a second set time longer than the first set time. . In addition, the number of times the temperature change rate of the evaporator is out of the normal change rate of the evaporator temperature may be stored, and if the number exceeds a preset number, a warning may be displayed to the outside.

In the present invention, the operating variable includes an indoor temperature and an outdoor temperature of the air conditioning system, and if the difference between the indoor temperature and the outdoor temperature is less than a preset temperature, the second control mode may be performed for a first preset time. Can be.

In the present invention, the operating variable includes a current applied to the compressor, and when the current change rate is out of a preset current change rate, the second control mode is performed for a first preset time.

In the present invention, the operation variable includes the discharge temperature of the compressor, the inlet side temperature of the evaporator, the indoor temperature and the outdoor temperature of the air conditioning system, and the current applied to the compressor, the discharge of the compressor When the temperature is within the normal operating range, the inlet temperature of the evaporator is detected, If the inlet temperature of the evaporator is within the normal operating range, the indoor temperature and outdoor temperature of the air conditioning system is detected, and the air conditioning When the difference between the indoor temperature and the outdoor temperature of the system is within the normal operating range, the current applied to the compressor may be sensed and compared with the normal operating range.

According to the present invention, when the operating variable value is out of the normal operating range, by shielding the injection valve, the liquid refrigerant is prevented from being injected into the compressor, so that the stability of the system can be improved.

The air conditioning system includes a general air conditioning air conditioner for performing only cooling operation, a heating air conditioner for performing only heating operation, a heat pump type air conditioner for performing both cooling and heating operation, a plurality of indoor spaces for cooling / It includes all multi-type air conditioners. Hereinafter, a heat pump type air conditioner (hereinafter referred to as an " air conditioner ") will be described in detail as an embodiment of an air conditioning system.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of an air conditioner 100 according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a control flow of the air conditioner 100. Referring to FIG.

1 and 2, the air conditioner 100 includes a compressor 110, an indoor heat exchanger 120, an outdoor heat exchanger 130, a first expansion valve 141, a second expansion valve 142 A phase separator 150, and a four-way valve 160. The indoor heat exchanger 120 serves as an evaporator during cooling operation and as a condenser during heating operation. The outdoor heat exchanger 130 acts as a condenser during the cooling operation, and acts as an evaporator during the heating operation. The compressor (110) compresses the introduced low-temperature low-pressure refrigerant into high-temperature high-pressure refrigerant. The compressor 110 includes a first compression unit 111 and a second compression unit 112. The first compression unit 111 compresses the refrigerant introduced from the evaporator and the second compression unit 112 compresses the refrigerant discharged from the first compression unit 111 and the refrigerant branched from the evaporator and the condenser, The refrigerant is mixed and compressed. However, the present invention is not limited to this, and the compressor 110 may have a multi-stage structure having three or more stages.

The four-way valve 160 guides the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 when it is cooled, and the indoor heat exchanger (120). The four-way valve 160 and the compressor 110 are connected to a first connection pipe 171. A compressor outlet temperature sensor 181 and a discharge pressure sensor 182 are disposed in the first connection pipe 171 to measure the discharge temperature and pressure of the refrigerant discharged from the compressor 110. The indoor heat exchanger 120 is disposed in the room and connected to the four-way valve 160 through a second connection pipe 172. The indoor heat exchanger (120) is provided with the indoor heat exchanger sensor (185).

The phase separator 150 separates the refrigerant flowing into the gas-phase refrigerant and the liquid-phase refrigerant, sends the liquid-phase refrigerant to the evaporator, and sends the gaseous refrigerant to the second compression unit 112. The first connection part 151 of the phase separator 150 and the indoor heat exchanger 120 are connected to the third connection pipe 173. The first connection part 151 is a liquid refrigerant discharge pipe during the cooling operation and a refrigerant inflow pipe during the heating operation.

The first expansion valve 141 is disposed on the third connection pipe 173 and is a second expansion device for exchanging the liquid refrigerant introduced from the phase separator 150 during cooling operation. And is a first expansion device for exchanging the liquid refrigerant introduced from the indoor heat exchanger (120).

The outdoor heat exchanger 130 is disposed outdoors and connected to the second connection unit 152 and the fourth connection pipe 174 of the phase separator 150. The outdoor heat exchanger (130) is provided with the outdoor heat exchanger sensor (186). The second connection portion 152 is a refrigerant inlet pipe during the cooling operation and a liquid refrigerant discharge pipe during the heating operation.

The second expansion valve 142 is disposed on the fourth connection pipe 174 and is a first expansion device for exchanging the liquid refrigerant introduced from the outdoor heat exchanger 130 during cooling operation. Is a second expansion device for exchanging the liquid refrigerant introduced from the phase separator (150).

The outdoor heat exchanger 130 is connected to the four-way valve 160 through a fifth connection pipe 175. In addition, the four-way valve 160 and the inflow pipe of the compressor 110 are connected to the sixth connection pipe 176. A compressor inlet temperature sensor 184 for measuring the temperature of the inlet side of the compressor 110 is disposed on the sixth connection pipe 176.

The second compression unit 112 is connected to the third connection unit 153 of the phase separator 150 through an injection pipe 180. The third connection part 153 is used as a gaseous refrigerant discharge pipe in the cooling and heating operation. An injection valve 143 is disposed on the injection pipe 180. The injection valve 143 controls the amount of refrigerant and the refrigerant pressure injected from the phase separator 150 to the second compression unit 112. When the injection valve 143 is opened, the gaseous refrigerant in the phase separator 150 flows into the second compression unit 112 through the injection pipe 180. An injection temperature sensor 183 for measuring the temperature of the injected refrigerant is disposed on the injection pipe 180.

The amount of opening of the first and second expansion valves 141 and 142 and the injection valve 143 is controlled by a control unit 200 that controls the operation of the air conditioner.

3 shows the flow of the refrigerant during the heating operation of the air conditioner.

3, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 flows into the indoor heat exchanger 120 via the four-way valve 160. [ The gaseous refrigerant in the indoor heat exchanger (120) undergoes heat exchange with the room air and is condensed. The condensed refrigerant is throttled in the first expansion valve 141, and then flows into the phase separator 160. The liquid refrigerant separated in the phase separator 160 is again throttled by the second expansion valve 142, and then flows into the outdoor heat exchanger 130. In the outdoor heat exchanger (130), the refrigerant evaporates due to heat exchange with the outside air, and the evaporated refrigerant flows into the first compression section (111).

When the operation of gas injection is requested during the heating operation, the control unit 200 opens the injection valve 143. The injection valve 143 is opened and the gaseous refrigerant separated by the phase separator 160 is injected into the second compression unit 112 through the injection pipe 180. [ In the second compression unit 112, the injected refrigerant and the refrigerant from the first compression unit 111 are mixed and then compressed. The refrigerant compressed by the second compression unit 112 circulates back to the four-way valve 160.

4 shows the flow of the refrigerant during the cooling operation of the air conditioner.

4, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 110 flows into the outdoor heat exchanger 130 through the four-way valve 160. In the outdoor heat exchanger (130), the gaseous refrigerant undergoes heat exchange with indoor air and is condensed. The condensed refrigerant is throttled in the second expansion valve 142, and then flows into the phase separator 150. The liquid refrigerant separated in the phase separator 150 is again throttled in the first expansion valve 141 and then flows into the indoor heat exchanger 120. [ In the indoor heat exchanger (120), the refrigerant evaporates due to heat exchange with the outside air, and the evaporated refrigerant flows into the first compression section (111). The control unit 200 shuts the injection valve 143 so that the gaseous refrigerant from the phase separator 150 is not injected into the second compression unit 112. However, the present invention is not limited to this, and the gaseous refrigerant from the phase separator 150 may be injected into the second compression unit 112 even during the cooling operation.

A control method of an air conditioner according to an embodiment of the present invention will now be described.

When the user drives the air conditioner 100 in order to heat and cool the indoor space, the controller 200 senses a driving command.

When the driving command is detected, the control unit 200 initializes the first and second expansion valves 141 and 142 and the injection valve 143. (S1) The control unit 200 controls the first, The two expansion valves 141 and 142 are completely opened, and the injection valve 143 is shielded. By shielding the injection valve 143, it is possible to prevent the liquid refrigerant from flowing into the compressor 110 at an initial stage of driving.

When the initialization of the first and second expansion valves 141 and 142 is completed, the controller 200 controls the amount of opening of the first expansion valve 141 and the second expansion valve 142 And controls them in different control modes from among a plurality of control modes. (S2) the plurality of control modes control the opening degree of the first expansion device to throttle the refrigerant flowing out of the condenser and introduced into the phase separator 150, thereby allowing the refrigerant to reach a predetermined intermediate pressure. Pressure control mode and the amount of opening of the second expansion device for throttling the refrigerant flowing out of the phase separator 150 into the evaporator, the refrigerant of the air conditioner 100 is a predetermined target superheat degree It also includes a superheat control mode to reach.

When the air conditioner 100 is in the heating operation mode, the first expansion valve 141 functions as the first expansion device, and the second expansion valve 142 functions as the second expansion device . Therefore, in the heating operation mode, the controller 200 controls the first expansion valve 141 to the intermediate pressure control mode, and controls the second expansion valve 142 to the superheat degree control mode. On the other hand, when the air conditioner 100 is in the cooling operation mode, the first expansion valve 141 serves as the second expansion device, and the second expansion valve 142 is the first expansion device. Therefore, the first expansion valve 141 is controlled in the superheat control mode, and the second expansion valve 142 is controlled in the intermediate pressure control mode.

The medium pressure control mode detects a driving variable value of at least one operating variable and determines a target opening degree of the valve based on a pre-stored set value corresponding to the detected operating variable value. The operating parameters are a plurality of operating parameters. The operating parameters include at least one of the following: whether or not the refrigerant is injected into the second compression unit 112, the gas injection operation, the frequency of the compressor 110, the indoor temperature of the air conditioner 100, The discharge pressure of the compressor 110, the discharge temperature of the compressor 110, and the like. The set values for the operating parameter values of the operating parameters are predetermined and stored in the form of a table in the controller 200. [ The set value for the frequency of the compressor 110 is set differently depending on whether the gas injection operation is performed or not. That is, the set value for the frequency of the compressor 110 is set differently depending on whether the injection valve 143 is open or closed. The target opening degree of the valve may be obtained by a combination of adding or multiplying the set values.

In the superheat degree control mode, the superheat degree of the refrigerant is measured in real time, and the opening amount of the valve is controlled based on the measured superheat degree. The degree of superheat of the refrigerant can be measured by the outdoor heat exchanger sensor 186 installed in the outdoor heat exchanger 130 and the compressor inlet temperature sensor 184. [ The control unit 200 stores a fuzzy table based on the measured superheat, the error of the predetermined target superheat degree, and the error variation amount, and the opening amount of the valve can be determined from the fuzzy table.

5 is a flowchart illustrating a control method of an injection valve of the air conditioner shown in FIG. 1.

Referring to FIG. 5, when there is a request for operation of the gas injection (S3), the control unit 200 controls the injection valve 143 in a first control mode. In the first control mode, the opening degree of the injection valve 143 is gradually opened until the target opening degree is reached. (S4) Therefore, the refrigerant of the gaseous phase separated from the phase separator 150 is discharged. To be introduced to the compression unit 112.

While the injection valve 143 is opened and the gas phase refrigerant is injected into the second compression unit 112, the controller 200 determines whether a liquid phase refrigerant is included in the injected refrigerant. When a liquid refrigerant is injected into the compressor 110, the liquid compression occurs in the compressor 110. When the liquid compression occurs, the operating variable value of the operating variable of the air conditioner 100 is out of a preset normal operating range. Therefore, the control unit 200 determines whether the operation variable value of at least one operating variable is out of a predetermined normal operating range, and if out of the predetermined normal operating range, the injection valve in the first control mode. Switch to the second control mode that shields (143). The control unit 200 is applied to the discharge temperature of the second compression unit 112, the temperature of the outdoor heat exchanger 130, the indoor temperature and the outdoor temperature of the air conditioner 100, the compressor 110 From the change in current or the like, it is possible to determine whether the liquid refrigerant is contained in the refrigerant to be injected.

First, the control unit 200 senses the discharge temperature of the second compression unit 112, and determines whether the discharge temperature change rate is out of a predetermined discharge temperature normal change rate (S5), that is, the discharge temperature. Determines whether the temperature drops below the set temperature within the set time. For example, when the discharge temperature drops by 15 degrees or more within 3 minutes, it is determined that the discharge temperature is out of the normal change rate, and it may be determined that the liquid compression occurs in the compressor 110. Here, the compressor 110 is turned off or the drop in the discharge temperature due to the frequency drop of the compressor 110 is excluded.

When the discharge temperature of the second compression unit 112 is out of the normal discharge rate of the discharge temperature, the controller 200 performs a second control mode for shielding the injection valve 143 for a first predetermined time. S7) The first set time for performing the second control mode may be obtained by experiment or the like. The control unit 200 may prevent the injection of the liquid refrigerant from the phase separator 150 to the second compression unit 112 by shielding the injection valve 143. The cumulative number of abnormalities of the discharge temperature at which the discharge temperature change rate deviates from the discharge temperature normal change rate is accumulated and summed. (S6)

On the other hand, if the discharge temperature change rate of the second compression unit 112 is within the normal discharge rate of the discharge temperature, by detecting the inlet temperature of the evaporator, whether the temperature change rate of the inlet side of the evaporator is outside the preset evaporator temperature normal change rate. (S8) That is, it is determined whether or not the temperature at the inlet side of the evaporator drops beyond the set temperature within the set time. Here, after the compressor 110 is driven, after the predetermined time has elapsed and the cycle is stabilized, it is preferable to sense the temperature at the inlet side of the evaporator. When the rate of change of the inlet side temperature of the evaporator is outside the normal rate of change of the evaporator temperature, the controller 200 performs a second control mode for shielding the injection valve 143 for the first predetermined time. By shielding the injection valve 143, it is possible to prevent the liquid refrigerant from being injected from the phase separator 150 to the second compression unit 112. And, the temperature change rate of the inlet side of the evaporator stores the number of abnormal times of the evaporator temperature outside the normal change rate of the evaporator temperature, and accumulates and sums them. (S9)

On the other hand, if it is determined that the rate of change of the inlet side temperature of the evaporator is within the normal rate of change of the evaporator temperature, the difference between the indoor temperature and the outdoor temperature of the air conditioner 100 is calculated, and whether the difference is less than a preset set temperature. If the difference between the indoor temperature and the outdoor temperature is less than the set temperature, the cycle may be abnormally rotated or the load of the air conditioner 100 may be very small. When the load of the air conditioner 100 is very small, injection of the gaseous refrigerant is unnecessary, and when unnecessary injection is made, the liquid refrigerant may be introduced into the compressor 110. Therefore, the controller 200 switches to the second control mode that shields the injection valve 143 to block the injection of the refrigerant in the gas phase into the compressor 110.

On the other hand, if the difference between the indoor temperature and the outdoor temperature of the air conditioner 100 is greater than or equal to the set temperature, the controller 200 detects a current change rate applied to the compressor 110 (S11). It is determined whether the current change rate applied to 110 is out of the preset current change rate. That is, when the current applied to the compressor 110 rises above the preset value within a preset time, it may be determined that liquid compression occurs and the work of the compressor is increased. Therefore, the control unit 200 performs the second control mode for shielding the injection valve 143 for the first predetermined time, thereby suspending the injection of the refrigerant.

On the other hand, when the abnormal number of times of the discharge temperature of the second compression unit 112 occurs more than a predetermined number of times (S12), the control unit 200 shields the injection valve 143 for a second set time (S13). The second set time may be set longer than the first set time.

In addition, when the abnormal number of times of the evaporator temperature occurs more than a predetermined number of times, the control unit 200 shields the injection valve 143 for the second set time (S13).

Therefore, if the discharge temperature of the second compressor 112 or the temperature of the evaporator frequently deviates from the normal operating range while the air conditioner 100 is continuously operated, the injection valve 143 is shielded. Increasing the time it takes to allow enough time for the cycle to stabilize. In addition, a warning message or a warning sound can be notified to the outside. (S14)

1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the control flow of the air conditioner shown in FIG. 1. FIG.

3 is a configuration diagram showing the flow of the refrigerant during the heating operation of the air conditioner shown in Fig.

FIG. 4 is a configuration diagram showing the flow of the refrigerant during the cooling operation of the air conditioner shown in FIG.

5 is a flowchart illustrating a control method of an injection valve of the air conditioner shown in FIG. 1.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

100: air conditioner 110: compressor

120: indoor heat exchanger 130: outdoor heat exchanger

141: first expansion valve 142: second expansion valve

143: Injection valve 150: Phase separator

160: Four-way valve 180: Injection piping

200:

Claims (13)

A condenser for condensing the refrigerant; A first expansion device through which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant having passed through the first expansion device is throttled; An evaporator through which the refrigerant having passed through the second expansion device is evaporated; A refrigerant passing through the evaporator and a compressor into which a refrigerant branched and injected between the first expansion device and the second expansion device flows and is compressed; An injection valve that is branched between the first expansion device and the second expansion device and throttles the refrigerant injected into the compressor; A second control to control the first control mode to open the injection valve and to switch the first control mode to shield the injection valve when the operation variable value of at least one operation variable is out of a preset normal operation range. Mode control, The operation variable includes a discharge temperature of the compressor, an inlet temperature of the evaporator, an indoor temperature and an outdoor temperature of an air conditioning system, and a current applied to the compressor, If at least one of the operation variable values of the operation variable is out of the normal operation range, the control unit switches from the first control mode to the second control mode and first sets the opening amount of the injection valve to the second control mode. Control over time, Store the number of times the operation variable value is outside the normal operation range, And performing the second control mode for a second preset time longer than the first preset time if the number of times exceeds the preset number. delete delete delete A condenser for condensing the refrigerant; A first expansion device through which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant having passed through the first expansion device is throttled; An evaporator through which the refrigerant having passed through the second expansion device is evaporated; A refrigerant passing through the evaporator and a compressor into which a refrigerant branched and injected between the first expansion device and the second expansion device flows and is compressed; An injection valve that is branched between the first expansion device and the second expansion device and throttles the refrigerant injected into the compressor; A second control to control the first control mode to open the injection valve and to switch the first control mode to shield the injection valve when the operation variable value of at least one operation variable is out of a preset normal operation range. Mode control, The operation variable includes a discharge temperature of the compressor, When the discharge temperature change rate of the compressor is out of a preset discharge temperature normal change rate, the second control mode is performed for a first preset time, Storing the number of times that the discharge temperature change rate of the compressor deviates from the normal discharge rate of the discharge temperature, And the second control mode is continued for a second set time longer than the first set time if the number exceeds the preset number. delete The method of claim 5, And displaying a warning to the outside when the discharge temperature change rate of the compressor exceeds the preset number of times when the discharge temperature change rate deviates from the discharge temperature normal change rate. A condenser for condensing the refrigerant; A first expansion device through which the refrigerant passing through the condenser is throttled; A second expansion device in which the refrigerant having passed through the first expansion device is throttled; An evaporator through which the refrigerant having passed through the second expansion device is evaporated; A refrigerant passing through the evaporator and a compressor into which a refrigerant branched and injected between the first expansion device and the second expansion device flows and is compressed; An injection valve that is branched between the first expansion device and the second expansion device and throttles the refrigerant injected into the compressor; A second control to control the first control mode to open the injection valve and to switch the first control mode to shield the injection valve when the operation variable value of at least one operation variable is out of a preset normal operation range. Mode control, The operating variable includes the temperature of the evaporator, and when the temperature change rate of the evaporator is out of a preset evaporator temperature normal change rate, the second control mode is performed for a first set time, Storing the number of times that the temperature change rate of the evaporator is outside the normal change rate of the evaporator temperature, And the second control mode is continued for a second set time longer than the first set time if the number exceeds the preset number. delete The method of claim 8, And displaying a warning to the outside when the temperature change rate of the evaporator exceeds a preset number of times that the temperature change rate of the evaporator is outside the normal change rate of the evaporator temperature. The method according to any one of claims 1, 5 and 8, Wherein the compressor includes a first compression section in which a refrigerant passing through the evaporator flows and is compressed, and a refrigerant that is branched and injected between the first expansion device and the second expansion device, And a second compression unit that compresses the compressed air. delete delete

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