JP2023140445A - Chilling unit, control method and program - Google Patents

Abstract

To provide a chilling unit capable of speedily detecting abnormality of a water heat exchanger.SOLUTION: A chilling unit comprises: a coolant circuit which has a compressor compressing a coolant, an air heat exchanger performing heat exchange between the coolant and external air, a water heat exchanger performing heat exchange between the coolant and water, an expansion valve installed between the air heat exchanger and the water heat exchanger, and a four-way valve switching a flow passage of the coolant between a cooling operation flow passage and a heating operation passage; a water circuit which has water piping inserted into the water heat exchanger, a water pump pumping the water into the water piping, and a water valve positioned on a downstream side of the water heat exchanger on the water piping; and a control device which controls the coolant circuit and the water circuit. The control device has a detection section which detects abnormality of the water heat exchanger when a saturation temperature on a low-pressure side or a high-pressure side of the coolant circuit is less than a predetermined lower limit saturation temperature.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a chilling unit, a control method, and a program.

In a chilling unit, if the heat exchanger between refrigerant and water (hereinafter also referred to as "water heat exchanger") is damaged due to freezing or corrosion caused by water quality, refrigerant leaks from the refrigerant circuit to the water circuit. There are cases where Patent Document 1 describes that refrigerant leakage is detected when the concentration of refrigerant exceeds a reference value for a certain period of time or more.

JP2020-51738A

If the chilling unit continues to operate with the water heat exchanger damaged, water may enter the refrigerant circuit if the pressures of the refrigerant circuit and the water circuit are equalized. If water enters the refrigerant circuit, it will be necessary to replace not only the water heat exchanger but also the compressor, accumulator, receiver, and valves (expansion valve, four-way valve, etc.) connected to the refrigerant circuit during repair. Repair costs and the number of days required for recovery may be high. Therefore, it is desired to quickly detect abnormalities such as damage to the water heat exchanger so that damage does not spread.

The present disclosure has been made in view of such problems, and provides a chilling unit, a control method, and a program that can quickly detect abnormalities in a water heat exchanger.

According to one aspect of the present disclosure, the chilling unit includes a compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, and a water heat exchanger that exchanges heat between the refrigerant and water. A refrigerant circuit including an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path. , a water circuit having a water pipe inserted into the water heat exchanger, a water pump for delivering the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe; , a control device that controls the refrigerant circuit and the water circuit, and the control device controls the water circuit when the saturation temperature of the low-pressure side or the high-pressure side of the refrigerant circuit is less than a predetermined lower limit of saturation temperature. It has a detection section that detects an abnormality in the heat exchanger.

According to one aspect of the present disclosure, a control method includes: a compressor that compresses a refrigerant; an air heat exchanger that exchanges heat between the refrigerant and outside air; a water heat exchanger that exchanges heat between the refrigerant and water; A refrigerant circuit including an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path. , a water circuit having a water pipe inserted into the water heat exchanger, a water pump for delivering the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe; , a control device for controlling a chilling unit, comprising: a control device for controlling the refrigerant circuit and the water circuit; The method further includes the step of detecting an abnormality in the water heat exchanger when the water heat exchanger is less than or equal to the water heat exchanger.

According to one aspect of the present disclosure, the program includes: a compressor that compresses a refrigerant; an air heat exchanger that exchanges heat between the refrigerant and outside air; a water heat exchanger that exchanges heat between the refrigerant and water; a refrigerant circuit having an expansion valve provided between an air heat exchanger and the water heat exchanger, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path; a water circuit having a water pipe inserted into the water heat exchanger, a water pump that sends the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe; A program that causes a control device of a chilling unit comprising: to execute a step of detecting an abnormality in the water heat exchanger when a saturation temperature on a low pressure side or a high pressure side of the refrigerant circuit is less than a predetermined lower limit value of saturation temperature.

According to the chilling unit, control method, and program according to the present disclosure, it is possible to quickly detect an abnormality in a water heat exchanger.

FIG. 2 is a first diagram showing the configuration of the chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of a control state during cooling operation. FIG. 2 is a second diagram illustrating the configuration of the chilling unit according to the first embodiment of the present disclosure, and is a diagram illustrating an example of a control state during heating operation. FIG. 7 is a third diagram illustrating the configuration of the chilling unit according to the first embodiment of the present disclosure, and is a diagram illustrating an example of a control state when the operation is stopped. FIG. 1 is a diagram showing a functional configuration of a control device according to a first embodiment of the present disclosure. FIG. 2 is a flowchart illustrating an example of processing during cooling operation of the control device according to the first embodiment of the present disclosure. FIG. FIG. 3 is a diagram illustrating an example of a control state when refrigerant leakage of the chilling unit according to the first embodiment of the present disclosure is detected. FIG. 2 is a flowchart illustrating an example of processing during heating operation of the control device according to the first embodiment of the present disclosure. FIG. It is a flowchart which shows an example of processing at the time of operation stop of a control device concerning a 1st embodiment of this indication.

<First embodiment>
A chilling unit according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 8.

(Overall configuration of chilling unit)
FIG. 1 is a first diagram showing the configuration of a chilling unit according to a first embodiment of the present disclosure, and is a diagram showing an example of a control state during cooling operation.
FIG. 2 is a second diagram showing the configuration of the chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of a control state during heating operation.
FIG. 3 is a third diagram showing the configuration of the chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of a control state when the operation is stopped.
As shown in FIGS. 1 to 3, the chilling unit 1 includes a refrigerant circuit 2, a water circuit 3, and a control device 4.

The refrigerant circuit 2 includes a compressor 21 , a four-way valve 22 , a water heat exchanger 23 , an expansion valve 24 , a receiver 25 , an air heat exchanger 26 , and an accumulator 27 . Each device of the refrigerant circuit 2 is connected by a refrigerant pipe 20.

The compressor 21 compresses the refrigerant R and supplies the compressed refrigerant R to the refrigerant circuit 2.

The four-way valve 22 switches between cooling operation and heating operation by switching the flow path of the refrigerant circuit 2. As shown in FIG. 1, the four-way valve 22 sends the refrigerant R discharged from the compressor 21 during cooling operation to the air heat exchanger 26. Further, as shown in FIG. 2, the four-way valve 22 sends the refrigerant R discharged from the compressor 21 during heating operation to the water heat exchanger 23.

The water heat exchanger 23 cools or heats the water W by exchanging heat between the refrigerant R and the water W.

The expansion valve 24 includes a mechanism that reduces the pressure of the refrigerant R when the refrigerant R passes therethrough. As shown in FIG. 1, the expansion valve 24 includes a first expansion valve 241, a second expansion valve 242, and a third expansion valve 243. The first expansion valve 241 is an expansion valve for cooling operation. The second expansion valve 242 and the third expansion valve 243 are expansion valves for heating operation. Further, the second expansion valve 242 is provided between the water heat exchanger 23 and the receiver 25, and the third expansion valve 243 is provided between the receiver 25 and the air heat exchanger 26.

During the cooling operation, as shown in FIG. 1, the first expansion valve 241 is in the open state, and the second expansion valve 242 and the third expansion valve 243 are in the closed state. During the heating operation, as shown in FIG. 2, the first expansion valve 241 is in the closed state, and the second expansion valve 242 and the third expansion valve 243 are in the open state. Further, when the operation is stopped, as shown in FIG. 3, the first expansion valve 241 and the third expansion valve 243 are in a closed state, and the second expansion valve 242 is in an open state.

The receiver 25 is a container for storing at least a portion of the liquid refrigerant that has passed through the second expansion valve 242 or the third expansion valve 243.

The air heat exchanger 26 exchanges heat between the refrigerant R and the outside air taken in by the propeller fan 261.

The accumulator 27 is a device that is provided upstream of the compressor 21 and separates liquid refrigerant and gaseous refrigerant. Of the refrigerants separated by the accumulator 27, only gaseous refrigerant is sent to the compressor 21.

Further, the refrigerant circuit 2 is provided with a plurality of sensors for measuring the pressure and temperature of the refrigerant R. A high-pressure side sensor 201 that measures the high-pressure side pressure (HP) of the refrigerant R is provided in the refrigerant pipe 20 between the compressor 21 and the four-way valve 22 (downstream of the compressor 21). A low-pressure side sensor 202 that measures the low-pressure side pressure (LP) of the refrigerant R is provided in the refrigerant pipe 20 between the accumulator 27 and the four-way valve 22 (on the upstream side of the accumulator 27). Further, a first temperature sensor 203 that measures the temperature of the refrigerant R is provided in the refrigerant pipe 20 between the expansion valve 24 and the air heat exchanger 26. The measurement values measured by each sensor are sequentially transmitted to the control device 4.

The water circuit 3 includes a water pipe 30, a water pump 31, and a water valve 32. The water pipe 30 is inserted into the water heat exchanger 23. The water pump 31 is provided upstream of the water heat exchanger 23 in the water pipe 30 and sends water W to the water pipe 30 from the outside. The temperature of the water W sent out by the water pump 31 is adjusted by exchanging heat with the refrigerant R while passing through the water heat exchanger 23. The water valve 32 is provided downstream of the water heat exchanger 23 in the water pipe 30. When the water valve 32 is opened, the temperature-adjusted water W is discharged to the outside through the water pipe 30. Moreover, when the water valve 32 is closed, the discharge of water W to the outside is stopped.

Further, the water circuit 3 is provided with a plurality of sensors for measuring the pressure and temperature of the water W. The water pipe 30 on the upstream side of the water heat exchanger 23 is provided with a first water pressure sensor 301 that measures the pressure (WP1) of the water W on the inlet side of the water heat exchanger 23. A second water pressure sensor 302 is provided in the water pipe 30 on the downstream side of the water heat exchanger 23 to measure the pressure (WP2) of the water W on the outlet side of the water heat exchanger 23. Further, a second temperature sensor 303 that measures the temperature of the water W is provided in the water pipe 30 on the downstream side (near the outlet) of the water heat exchanger 23. The measurement values measured by each sensor are sequentially transmitted to the control device 4.

The control device 4 controls the operation of each device in the refrigerant circuit 2 and the water circuit 3, and puts the chilling unit 1 into one of a cooling operation, a heating operation, and a shutdown state.

Further, the control device 4 according to the present embodiment detects an abnormality in the water heat exchanger 23 based on the measured values received from each sensor of the refrigerant circuit 2 and the water circuit 3. Furthermore, when the control device 4 detects a sign of leakage of the refrigerant R in the water heat exchanger 23, it executes a process of suppressing the intrusion of water W into the refrigerant circuit 2. Details of this processing will be described later.

(Functional configuration of control device)
FIG. 4 is a diagram showing a functional configuration of a control device according to the first embodiment of the present disclosure.
As shown in FIG. 4, the control device 4 includes a processor 40, a main memory 41, a storage 42, an interface 43, and a display section 44.

The processor 40 functions as a detection section 401, a control section 402, and an alarm section 403 by operating according to a predetermined program.

The detection unit 401 detects an abnormality in the water heat exchanger 23 based on the measured values of each sensor provided in the refrigerant circuit 2 and the water circuit 3. Specifically, the detection unit 401 detects a low pressure abnormality in the water heat exchanger 23 when the saturation temperature of the refrigerant R is less than a predetermined lower limit value of the saturation temperature. Furthermore, the detection unit 401 further detects the presence or absence of a sign of leakage of the refrigerant R from the water heat exchanger 23 during each of the cooling operation, the heating operation, and the stoppage of the operation.

When the control unit 402 detects a sign of leakage of the refrigerant R from the water heat exchanger 23, it executes various processes to suppress the intrusion of water W into the refrigerant circuit 2.

The alarm unit 403 issues an abnormality alarm through the display unit 44 when an abnormality in the water heat exchanger 23 is detected. Note that the alarm unit 403 may issue an abnormality alarm to an external monitoring terminal (computer, smartphone, tablet, etc.) through the interface 43.

The main memory 41 stores instructions and data for the processor 40 to operate based on a program.

The storage 42 is a so-called auxiliary storage device, and may be, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive).

The interface 43 is an interface (communication interface) for communicably connecting each device and sensor of the refrigerant circuit 2 and the water circuit 3.

The display unit 44 is a display that displays information such as whether or not there is an abnormality in the chilling unit 1.

(Processing flow during cooling operation)
FIG. 5 is a flowchart illustrating an example of processing during cooling operation of the control device according to the first embodiment of the present disclosure.
Hereinafter, with reference to FIG. 5, a process for monitoring an abnormality in the water heat exchanger 23 during cooling operation and a process flow when an abnormality occurs will be described.

The control unit 402 controls the operating state of each device in the refrigerant circuit 2 and the water circuit 3 to perform cooling operation of the chilling unit 1 (step S100). For example, as shown in FIG. 1, the control unit 402 switches the four-way valve 22 so that the refrigerant R discharged from the compressor 21 flows to the air heat exchanger 26, and also switches the four-way valve 22 so that the first expansion valve 241 is open and the second The expansion valve 242 and the third expansion valve 243 are closed. When the compressor 21 is operated in this manner, the four-way valve 22 is switched and becomes a refrigerant circuit for cooling operation. Before operating the compressor 21, the control unit 402 operates the water pump 31 in the water circuit 3 and opens the water valve 32, if installed. Thereby, the water W flowing through the water circuit 3 is cooled by the refrigerant R while passing through the water heat exchanger 23 .

Furthermore, during the cooling operation, the detection unit 401 constantly monitors the measured value of the low-pressure side sensor 202 of the refrigerant circuit 2 (the pressure LP on the low-pressure side of the refrigerant R), and detects whether or not there is an abnormality in the refrigerant pressure. In the present embodiment, each time the detection unit 401 receives a measurement value from the low pressure side sensor 202, the detection unit 401 determines whether the low pressure side saturation temperature (hereinafter also referred to as "LP saturation temperature") is the first saturation temperature lower limit (e.g. , -A° C.) (step S101). For example, a correspondence table of saturation pressure and saturation temperature for each type of refrigerant R is recorded in advance in the storage 42, and the detection unit 401 refers to the correspondence table to determine the LP saturation temperature. Further, the first saturation temperature lower limit value is set in advance depending on the type of refrigerant R and the like.

If the LP saturation temperature is equal to or higher than the first saturation temperature lower limit (step S101: NO), the detection unit 401 determines that the pressure state of the refrigerant is normal. In this case, the control device 4 continues the cooling operation of the chilling unit 1.

On the other hand, when the LP saturation temperature is less than the first saturation temperature (step S101: YES), the detection unit 401 detects that an abnormality has occurred in the low pressure of the refrigerant. In this case, the control unit 402 stops the cooling operation of the chilling unit 1. Further, the alarm unit 403 issues an abnormality alarm indicating an abnormality in the refrigerant circuit 2 (step S102). At this time, the alarm unit 403 may display the value of the LP saturation temperature and the like on the display unit 44 together with the abnormality alarm. Further, the alarm unit 403 may issue an abnormality alarm to an external monitoring terminal or the like through the interface 43. The administrator of the chilling unit 1 arranges for repair of the chilling unit 1 when a refrigerant low pressure abnormality alarm is issued.

Next, the detection unit 401 checks whether there is any sign of leakage of the refrigerant R into the water circuit 3 in the water heat exchanger 23 . Specifically, first, the detection unit 401 determines the degree of supercooling at the outlet of the air heat exchanger 26 based on the measurement value of the first temperature sensor 203 immediately before the low pressure abnormality occurred. Note that in other embodiments, the first temperature sensor 203 is a sensor capable of measuring the degree of subcooling, and the detection unit 401 acquires the degree of subcooling at the outlet of the air heat exchanger 26 from the first temperature sensor 203. Good too. Then, the detection unit 401 determines whether the degree of supercooling at the outlet of the air heat exchanger 26 has significantly decreased from a predetermined reference value for the degree of supercooling, and whether supercooling cannot be ensured (step S103). Note that the subcooling degree reference value is set in advance according to the type of refrigerant R and the like.

If the degree of supercooling at the outlet of the air heat exchanger 26 has not decreased below the degree of supercooling reference value (step S103: NO), the detection unit 401 determines that there is no sign of leakage of the refrigerant R (step S105). ). In this case, the control unit 402 finishes the process while stopping the operation of the chilling unit 1.

On the other hand, if the degree of supercooling at the outlet of the air heat exchanger 26 has decreased below the degree of supercooling reference value (step S103: YES), the detection unit 401 detects the water temperature in the water circuit 3 immediately before the low pressure abnormality occurred. It is further confirmed whether the water temperature at the outlet of the exchanger 23 is less than the lower limit of the water temperature control range (for example, 3° C.) (step S104). The lower limit value of the water temperature control range indicates a set temperature in a temperature range that can be set in the chilling unit 1. For example, if the settable temperature range is "4 to 30 degrees Celsius", if the set temperature is "4 degrees Celsius", the lower limit value is "4 degrees Celsius", and if the set temperature is "7 degrees Celsius", the lower limit value is It is "7℃".

When there is no refrigerant leakage at the time of low temperature abnormality (there is sufficient refrigerant R in the refrigerant circuit 2), the water temperature decreases as the pressure LP on the low pressure side decreases (supercooling occurs). Therefore, if the water temperature at the outlet of the water heat exchanger 23 measured by the second temperature sensor 303 is less than the lower limit of the water temperature control range (step S104: NO), the detection unit 401 detects that there is no sign of leakage of the refrigerant R. It is determined that there is no one (step S105). In other words, it is determined that the low pressure abnormality of the refrigerant is due to a cause other than refrigerant leakage from the water heat exchanger 23, for example, clogging of the refrigerant circuit 2. In this case, the control unit 402 finishes the process while stopping the operation of the chilling unit 1.

On the other hand, if there is a refrigerant leak during a low pressure abnormality, there will be a shortage of refrigerant R, making it difficult to perform sufficient cooling until the lower limit value (set temperature) is reached. Therefore, if the water temperature at the outlet of the water heat exchanger 23 is equal to or higher than the lower limit of the water temperature control range (step S104: YES), the detection unit 401 detects that a leak has already occurred in the water heat exchanger 23 and that the refrigerant and water It is determined that the water temperature cannot be controlled due to a mixture of In this case, the alarm unit 403 issues an abnormality alarm indicating refrigerant leakage from the water heat exchanger 23 (step S106). The administrator of the chilling unit 1 arranges for repair of the chilling unit 1 when an abnormality alarm indicating refrigerant leakage from the water heat exchanger 23 is issued.

Usually, the refrigerant circuit 2 has a higher pressure than the water circuit 3. However, if the leakage of the refrigerant R progresses and the refrigerant circuit 2 and the water circuit 3 become equalized in pressure, the water W in the water circuit 3 may enter the refrigerant circuit 2. Furthermore, it may take some time from when the repair is arranged until the chilling unit 1 is actually repaired. Therefore, if the leakage of the refrigerant R is left unaddressed until the chilling unit 1 is repaired, water W will enter the refrigerant circuit 2, causing damage to the compressor 21, etc. damage may be increased.

In order to reduce the possibility that such damage to the chilling unit 1 will expand, the control unit 402 according to the present embodiment automatically controls water W from entering the refrigerant circuit 2 when a refrigerant leak is detected. Execute processing. The specific contents of this process will be explained with reference to FIGS. 5 and 6.

FIG. 6 is a diagram illustrating an example of a control state when refrigerant leakage of the chilling unit according to the first embodiment of the present disclosure is detected.
First, the processing in the water circuit 3 will be explained. If the water heat exchanger 23 is damaged, water W may leak into the refrigerant circuit 2 if there is a flow of water W on the water circuit 3 side. Therefore, as shown in FIG. 6, the control unit 402 executes a third process of stopping the water pump 31 of the water circuit 3 and closing the water valve 32 (step S107). Thereby, intrusion of water W into the refrigerant circuit 2 can be suppressed. In addition, in a system in which multiple chilling units 1 are connected through one water circuit 3, if refrigerant R leaks into the water circuit 3 of a certain chilling unit 1, water W mixed with refrigerant R will leak to other chilling units. Circulation can be suppressed.

Further, processing in the refrigerant circuit 2 will be explained. The control unit 402 executes a first process (steps S108 to S109) of increasing the pressure of the refrigerant circuit 2 so that the refrigerant circuit 2 and the water circuit 3 are not pressure-equalized. Specifically, as shown in FIG. 6, the control unit 402 closes the first expansion valve 241 and the second expansion valve 242, opens the third expansion valve 243, and operates the four-way valve 22. to switch to the flow path for heating operation (step S108). The control unit 402 also starts the compressor 21 (step S109). In this way, the control unit 402 limits the flow path downstream of the compressor 21 to a short section up to the second expansion valve 242, and then sends out the refrigerant R compressed by the compressor 21. The pressure in the section from the compressor 21 to the second expansion valve 242 in the circuit 2, that is, the section before and after the water heat exchanger 23 is increased.

Furthermore, the control unit 402 executes a second process (steps S109 to S112) to maintain the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 within a certain range.

First, the control unit 402 checks whether the high pressure side pressure HP of the refrigerant circuit 2 measured by the high pressure side sensor 201 after starting the compressor 21 exceeds the pressure upper limit value (step S110). The pressure upper limit value is, for example, a value obtained by adding a predetermined margin α1 to the inlet side pressure WP1 of the water circuit 3 measured by the first water pressure sensor 301. The value of the margin α1 is set in advance according to the type of refrigerant R, the characteristics of the compressor 21, and the like.

When the high-pressure side pressure HP is below the pressure upper limit (step S110: NO), the control unit 402 continues the operation of the compressor 21.

On the other hand, when the high pressure side pressure HP exceeds the pressure upper limit value (step S110: YES), the control unit 402 stops the compressor 21 (step S111). Thereby, the control unit 402 can suppress the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 from becoming higher than necessary with respect to the pressure of the water circuit 3.

Further, after stopping the compressor 21, the control unit 402 checks whether the high pressure side pressure HP has become less than the lower pressure limit (step S112). The pressure upper limit value is, for example, a value obtained by adding a predetermined margin α2 to the inlet side pressure WP1 of the water circuit 3 measured by the first water pressure sensor 301. The value of the margin α2 is set in advance according to the type of refrigerant R, the characteristics of the compressor 21, and the like. Note that the values of the margins α1 and α2 may be the same or may be different.

If the high-pressure side pressure HP is equal to or higher than the lower pressure limit (step S112: NO), the control unit 402 keeps the compressor 21 stopped.

On the other hand, when the high pressure side pressure HP becomes less than the pressure lower limit value (step S112: YES), the control unit 402 starts the compressor 21 (returns to step S109). As a result, the control unit 402 can control the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 to be equalized with the water circuit 3, and prevent water W from entering the refrigerant circuit 2. can.

In this way, when a sign of leakage of the refrigerant R is detected during the cooling operation, the control unit 402 performs the first to third processes as shown in FIG. This prevents the damage to the chilling unit 1 from expanding.

(Processing flow during heating operation)
FIG. 7 is a flowchart illustrating an example of processing during heating operation of the control device according to the first embodiment of the present disclosure.
Hereinafter, with reference to FIG. 7, a process for monitoring an abnormality in the water heat exchanger 23 during heating operation and a process flow when an abnormality occurs will be described.

The control unit 402 controls the operating state of each device in the refrigerant circuit 2 and the water circuit 3 to perform heating operation of the chilling unit 1 (step S200). For example, as shown in FIG. 2, the control unit 402 switches the four-way valve 22 so that the refrigerant R discharged from the compressor 21 flows to the water heat exchanger 23, and also switches the first expansion valve 241 to the closed state and the second The expansion valve 242 and the third expansion valve 243 are opened. After switching the refrigerant circuit 2 to the heating operation flow path in this way, the control unit 402 operates the compressor 21. Regarding the water circuit 3, the control unit 402 operates the water pump 31 before operating the compressor 21, and opens the water valve 32 if it is installed. Thereby, the water W flowing through the water circuit 3 is heated by the refrigerant R while passing through the water heat exchanger 23 .

Furthermore, during the heating operation, the detection unit 401 constantly monitors the pressure LP on the low pressure side of the refrigerant R to detect whether or not there is an abnormality in the water heat exchanger 23. Specifically, the detection unit 401 monitors whether the outside air temperature is 0° C. or higher and the LP saturation temperature has become less than the second saturation temperature lower limit (for example, −B° C.) (step S201). Note that the second lower limit of saturation temperature is set in advance according to the type of refrigerant R and the like.

When the outside air temperature is less than 0° C. or when the LP saturation temperature is equal to or higher than the second saturation temperature lower limit (step S201: NO), the detection unit 401 determines that there is no abnormality in the refrigerant circuit 2 (no leakage). I judge that. In this case, the control device 4 continues the heating operation of the chilling unit 1.

On the other hand, if the outside air temperature is 0° C. or higher and the LP saturation temperature is less than the second saturation temperature (step S201: YES), the detection unit 401 detects that leakage has occurred from the refrigerant circuit 2 and that the There may be signs of leakage of refrigerant R in the heat exchanger 23. In this case, the control unit 402 stops the heating operation of the chilling unit 1. Further, the alarm unit 403 issues an abnormality alarm indicating a sign of refrigerant leakage from the water heat exchanger 23 (step S202).

When a sign of refrigerant leakage is detected, the control unit 402 executes a process of suppressing the infiltration of water W into the refrigerant circuit 2 in the same manner as during the cooling operation.

Regarding the water circuit 3, the control unit 402 executes a third process of stopping the water pump 31 of the water circuit 3 and closing the water valve 32 (step S203). This process is the same as step S107 in FIG.

Regarding the refrigerant circuit 2, first, the control unit 402 executes a first process (steps S204 to S205) of increasing the pressure of the refrigerant circuit 2 so that the refrigerant circuit 2 does not reach an equal pressure state with the water circuit 3. When the heating operation is stopped in step S202, the flow path may be switched to the flow path shown in FIG. 3 during which the operation is stopped. Therefore, as shown in FIG. 6, the control unit 402 closes the first expansion valve 241 and the second expansion valve 242 and opens the third expansion valve 243, and operates the four-way valve 22 to heat the The flow path is switched to the operating flow path (step S204). The control unit 402 also starts the compressor 21 (step S205) to increase the pressure in the section from the compressor 21 to the second expansion valve 242 in the refrigerant circuit 2, that is, the section before and after the water heat exchanger 23. let These processes are the same as steps S108 to S109 in FIG.

Further, the control unit 402 executes a second process (steps S205 to S208) to maintain the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 within a certain range. These processes are the same as steps S109 to S112 in FIG.

When a sign of leakage of the refrigerant R is detected during the heating operation, the control unit 402 performs the first to third processes as shown in FIG. W is suppressed from entering the refrigerant circuit 2.

(Processing flow when operation is stopped)
FIG. 8 is a flowchart illustrating an example of processing when the control device stops operating according to the first embodiment of the present disclosure.
Hereinafter, with reference to FIG. 8, a process for monitoring an abnormality in the water heat exchanger 23 when the operation is stopped and a flow of the process when an abnormality occurs will be described.

The control unit 402 brings the chilling unit 1 into a stopped state in accordance with the operation of the administrator of the chilling unit 1 or the like (step S300). At this time, as shown in FIG. 3, the control unit 402 closes the first expansion valve 241 and the third expansion valve 243, opens the second expansion valve 242, and stops the compressor 21. Further, the control unit 402 stops the water pump 31 and closes the water valve 32. Note that in other embodiments, the control unit 402 may operate the water pump 31 and keep the water valve 32 open even when the operation is stopped for protection control.

Further, the detection unit 401 constantly monitors the low-pressure side pressure LP or high-pressure side pressure HP of the refrigerant R during the shutdown to detect whether or not there is an abnormality in the water heat exchanger 23. Specifically, the detection unit 401 detects that the outside air temperature is 0° C. or higher, and the LP saturation temperature or the high pressure side saturation temperature (hereinafter also referred to as "HP saturation temperature") is the third saturation temperature lower limit. (for example, -C°C) or not (step S301). Note that the third lower limit of saturation temperature is set in advance depending on the type of refrigerant R and the like.

If the outside air temperature is less than 0°C, or if the LP saturation temperature or HP saturation temperature is equal to or higher than the third saturation temperature lower limit (step S301: NO), the detection unit 401 detects that there is no problem with the refrigerant circuit 2. It is determined that there is no abnormality in the water heat exchanger 23. In this case, the control device 4 keeps the chilling unit 1 in the stopped state.

On the other hand, if the outside air temperature is 0° C. or higher and the LP saturation temperature or HP saturation temperature is less than the third saturation temperature (step S301: YES), the detection unit 401 detects that leakage from the refrigerant circuit 2 has occurred. It is detected that there may be a sign of leakage of refrigerant R in the water heat exchanger 23. In this case, the alarm unit 403 issues an abnormality alarm indicating a sign of refrigerant leakage from the refrigerant circuit 2 (step S302).

When a sign of refrigerant leakage is detected, the control unit 402 executes a process of suppressing the infiltration of water W into the refrigerant circuit 2 in the same manner as during the cooling operation.

In the case of operation in which the water pump 31 is operated even when the operation is stopped, the control unit 402 executes a third process of stopping the water pump 31 of the water circuit 3 and closing the water valve 32 (step S303). This process is the same as step S107 in FIG. In addition, in the case of operation in which the water pump 31 is stopped during the operation stop, step S303 may be omitted.

Regarding the refrigerant circuit 2, the control unit 402 first executes a first process (steps S304 to S305) to increase the pressure of the refrigerant circuit 2 so that the refrigerant circuit 2 and the water circuit 3 are not pressure-equalized. These processes are the same as steps S108 to S109 in FIG.

Furthermore, the control unit 402 executes a second process (steps S305 to S308) to maintain the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 within a certain range. These processes are the same as steps S109 to S112 in FIG.

When a sign of leakage of the refrigerant R is detected during the shutdown, the control unit 402 performs the first to third processes as shown in FIG. W is suppressed from entering the refrigerant circuit 2.

Note that in step S301 of FIG. 8, the detection unit 401 according to the present embodiment detects conditions when the outside air temperature is 0° C. or higher and the LP saturation temperature or the HP saturation temperature is less than the third saturation temperature (condition 1 is satisfied). If the condition is met), it is detected that there is a sign of leakage of refrigerant R, and maintenance control is carried out assuming leakage from the water heat exchanger 23 in steps S303 to S308; however, the present invention is not limited to this. do not have. In another embodiment, in step S301, the detection unit 401 causes the refrigerant to flow into the water heat exchanger 23 when another condition (condition 2) is satisfied in place of condition 1 or in addition to condition 1. It may be detected that an indication of R leakage has occurred. When Condition 2 is satisfied, for example, the outside air temperature is 0° C. or higher, the difference between the LP saturation temperature (or HP saturation temperature) and the outside air temperature is a predetermined temperature difference (for example, 10 degrees) or more, and, This is a case where the change in LP saturation temperature (or HP saturation temperature) does not follow the change in outside air temperature. The detection unit 401 can detect refrigerant leakage of the refrigerant R by checking whether condition 2 is satisfied.

Note that in FIGS. 5, 7, and 8, the control unit 402 executes the first process (steps S108 to S109, S204 to S205, S304 to S305) after the third process (steps S107, S203, and S303). Although an example of processing is described, the order of processing is not limited to this. The control unit 402 may execute the third process after the first process or simultaneously with the first process.

(action, effect)
As described above, in the chilling unit 1 according to the present embodiment, the control device 4 controls the water heat exchanger 23 when the LP saturation temperature or HP saturation temperature of the refrigerant circuit 2 is less than the predetermined lower limit of the saturation temperature. It has a detection unit 401 that detects an abnormality.

By doing so, the chilling unit 1 can quickly detect an abnormality in the water heat exchanger 23.

Further, the detection unit 401 of the control device 4 detects that during the cooling operation, the LP saturation temperature of the refrigerant circuit 2 is less than the first saturation temperature lower limit value, and the degree of supercooling at the outlet of the air heat exchanger 26 is the degree of supercooling reference. When the water temperature at the outlet of the water heat exchanger 23 of the water circuit 3 is equal to or higher than the lower limit of the water temperature control range, an abnormality indicating refrigerant leakage in the water heat exchanger 23 is detected.

By doing so, the chilling unit 1 can quickly detect refrigerant leakage during cooling operation.

Further, the detection unit 401 of the control device 4 detects an abnormality indicating a sign of refrigerant leakage in the water heat exchanger 23 when the LP saturation temperature of the refrigerant circuit 2 is less than the second lower limit value of the saturation temperature during the heating operation. To detect.

By doing so, the chilling unit 1 can quickly detect signs of refrigerant leakage during heating operation.

Further, the detection unit 401 of the control device 4 detects a sign of refrigerant leakage in the water heat exchanger 23 when the LP saturation temperature or HP saturation temperature of the refrigerant circuit 2 is less than the third saturation temperature lower limit during the operation stop. Detects abnormalities that indicate

By doing so, the chilling unit 1 can quickly detect signs of refrigerant leakage during shutdown.

Further, when a sign of refrigerant leakage is detected, the control device 4 closes the first expansion valve 241 and the second expansion valve 242, switches the four-way valve 22 to a flow path for heating operation, and controls the compressor. The computer further includes a control unit 402 that executes a first process of activating 21.

By doing so, the chilling unit 1 maintains the state in which the refrigerant circuit 2 is at a higher pressure than the water circuit 3 until the water heat exchanger 23 is repaired or replaced, and the chilling unit 1 maintains the state in which the refrigerant circuit 2 is at a higher pressure than the water circuit 3. Infiltration of water W can be suppressed. Thereby, the possibility that each device connected to the refrigerant circuit 2 is damaged by water that has entered the refrigerant circuit 2 can be reduced.

Further, after executing the first process, the control unit 402 of the control device 4 stops the compressor 21 when the high-pressure side pressure HP of the refrigerant circuit 2 becomes equal to or higher than the pressure upper limit, and controls the high-pressure side pressure HP of the refrigerant circuit 2 to A second process of starting the compressor 21 when the pressure becomes less than the lower limit value is further executed.

By doing so, the chilling unit 1 can maintain the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 within a certain range. Thereby, it is possible to suppress water W from entering the refrigerant circuit 2 from the water circuit 3.

Further, the control unit 402 of the control device 4 sets the pressure lower limit value to a value obtained by adding a predetermined margin α2 to the inlet side pressure WP1 of the water circuit 3.

By doing so, the chilling unit 1 can maintain the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 to be higher than the pressure in the water circuit 3. Thereby, it is possible to more reliably suppress water W from entering the refrigerant circuit 2 from the water circuit 3.

Further, when detecting a sign of refrigerant leakage, the control unit 402 of the control device 4 further executes a third process of stopping the water pump 31 and closing the water valve 32.

By doing so, the flow of water W in the water circuit 3 can be reliably stopped, so that the intrusion of water W into the refrigerant circuit 2 can be suppressed. In addition, in a system in which multiple chilling units 1 are connected through one water circuit 3, if refrigerant R leaks into the water circuit 3 of a certain chilling unit 1, water W mixed with refrigerant R will leak to other chilling units. Circulation can be suppressed.

As described above, several embodiments according to the present disclosure have been described, but all these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

<Additional notes>
The chilling unit, control method, and program described in the above-described embodiments can be understood, for example, as follows.

(1) According to the first aspect of the present disclosure, the chilling unit (1) includes a compressor (21) that compresses a refrigerant, an air heat exchanger (26) that exchanges heat between the refrigerant and outside air, and a compressor (21) that compresses the refrigerant. The expansion valve (24) provided between the water heat exchanger (23), air heat exchanger (26), and water heat exchanger (23) that exchanges heat with water, and the refrigerant flow path are cooled. A refrigerant circuit (2) having a four-way valve (22) for switching to a flow path for operation or a flow path for heating operation, a water pipe (30) inserted into a water heat exchanger (23), and a water pipe (30). A water circuit (3) having a water pump (31) that sends water to the water pipe (30) and a water valve (32) provided on the downstream side of the water heat exchanger (23), and a refrigerant circuit ( 2) and a control device (4) that controls the water circuit (3), and the control device (4) is configured such that the saturation temperature of the low-pressure side or the high-pressure side of the refrigerant circuit (2) is less than a predetermined lower limit of saturation temperature. It has a detection unit (401) that detects an abnormality in the water heat exchanger (23) when the water heat exchanger (23) is abnormal.

By doing so, the chilling unit can quickly detect an abnormality in the water heat exchanger.

(2) According to the second aspect of the present disclosure, in the chilling unit (1) according to the first aspect, the detection unit (401) of the control device (4) detects the refrigerant circuit (2) during the cooling operation. The saturation temperature on the low pressure side of the air heat exchanger (26) is lower than the first saturation temperature lower limit, the degree of supercooling at the outlet of the air heat exchanger (26) is lower than the degree of supercooling reference value, and the water in the water circuit (3) is When the water temperature at the outlet of the heat exchanger (23) is equal to or higher than the lower limit of the water temperature control range, an abnormality indicating refrigerant leakage in the water heat exchanger (23) is detected.

By doing so, the chilling unit can quickly detect refrigerant leakage during cooling operation.

(3) According to the third aspect of the present disclosure, in the chilling unit (1) according to the first or second aspect, the detection unit (401) of the control device (4) detects the refrigerant circuit during the heating operation. (2) When the saturation temperature on the low pressure side is less than the second lower limit of saturation temperature, an abnormality indicating a sign of refrigerant leakage in the water heat exchanger (23) is detected.

By doing so, the chilling unit 1 can quickly detect signs of refrigerant leakage during heating operation.

(4) According to the fourth aspect of the present disclosure, in the chilling unit (1) according to any one of the first to third aspects, the detection unit (401) of the control device (4) In addition, when the saturation temperature on the low pressure side or the high pressure side of the refrigerant circuit (2) is less than the third lower limit of saturation temperature, an abnormality indicating a sign of refrigerant leakage in the water heat exchanger (23) is detected.

By doing so, the chilling unit can quickly detect signs of refrigerant leakage during shutdown.

(5) According to the fifth aspect of the present disclosure, in the chilling unit (1) according to any one of the second to fourth aspects, the control device (4) is configured to , further includes a control unit (402) that executes a first process of closing the expansion valve (24), switching the four-way valve (22) to become a flow path for heating operation, and starting the compressor (21). .

By doing this, the chilling unit maintains the refrigerant circuit at a higher pressure than the water circuit and prevents water from entering the refrigerant circuit until the water heat exchanger is repaired or replaced. Can be suppressed. This can reduce the possibility that each device connected to the refrigerant circuit will be damaged by water that has entered the refrigerant circuit.

(6) According to the sixth aspect of the present disclosure, in the chilling unit (1) according to the fifth aspect, the control unit (402) of the control device (4), after performing the first process, controls the refrigerant circuit ( The compressor (21) is stopped when the pressure on the high pressure side of 2) becomes equal to or higher than the pressure upper limit, and the compressor (21) is stopped when the pressure on the high pressure side of the refrigerant circuit (2) becomes less than the pressure lower limit. The second process to be activated is further executed.

By doing so, the chilling unit can maintain the pressure in the section before and after the water heat exchanger of the refrigerant circuit within a certain range. Thereby, it is possible to suppress water from entering the refrigerant circuit from the water circuit.

(7) According to the seventh aspect of the present disclosure, in the chilling unit (1) according to the sixth aspect, the control section (402) of the control device (4) sets the pressure lower limit value of the water circuit (3). Set to the value obtained by adding a predetermined margin to the measured value of the pressure on the inlet side.

By doing so, the chilling unit can maintain the pressure in the section before and after the water heat exchanger of the refrigerant circuit to be higher than the pressure in the water circuit. Thereby, it is possible to more reliably suppress water from entering the refrigerant circuit from the water circuit.

(8) According to the eighth aspect of the present disclosure, in the chilling unit (1) according to any one of the fifth to seventh aspects, the control unit (402) of the control device (4) is configured to prevent refrigerant leakage. When a symptom is detected, a third process of stopping the water pump (31) and closing the water valve (32) is further executed.

By doing so, the flow of water in the water circuit can be reliably stopped, so that it is possible to suppress water from entering the refrigerant circuit. In addition, in a system where multiple chilling units are connected through one water circuit, if refrigerant leaks into the water circuit of one chilling unit, this prevents the water mixed with the refrigerant from circulating to other chilling units. can do.

(9) According to the ninth aspect of the present disclosure, the control method includes a compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, and a water heat exchanger that exchanges heat between the refrigerant and water. A refrigerant circuit having an expansion valve provided between the exchanger, the air heat exchanger, and the water heat exchanger, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path. , a water circuit having a water pipe inserted into the water heat exchanger, a water pump that sends water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger, a refrigerant circuit, and a water pipe. A control method for a chilling unit comprising: a control device for controlling a circuit; The method includes the step of detecting an abnormality in the device.

(10) According to the tenth aspect of the present disclosure, the program includes a compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, and a water heat exchanger that exchanges heat between the refrigerant and water. a refrigerant circuit having an expansion valve provided between the refrigerant, the air heat exchanger, and the water heat exchanger, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path; A chilling unit comprising a water pipe inserted into a water heat exchanger, a water pump that sends water to the water pipe, and a water circuit having a water valve provided downstream of the water heat exchanger in the water pipe. The control device is caused to perform a step of detecting an abnormality in the water heat exchanger when the saturation temperature on the low pressure side or the high pressure side of the refrigerant circuit is less than a predetermined lower limit of saturation temperature.

1 Chilling unit 2 Refrigerant circuit 20 Refrigerant piping 201 High pressure side sensor 202 Low pressure side sensor 203 First temperature sensor 21 Compressor 22 Four-way valve 23 Water heat exchanger 24 Expansion valve 241 First expansion valve 242 Second expansion valve 243 Third expansion Valve 25 Receiver 26 Air heat exchanger 261 Propeller fan 27 Accumulator 3 Water circuit 301 First water pressure sensor 302 Second water pressure sensor 303 Second temperature sensor 30 Water piping 31 Water pump 32 Water valve 4 Control device 40 Processor 401 Detection unit 402 Control Section 403 Alarm section 41 Main memory 42 Storage 43 Interface 44 Display section

Claims (10)

A compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, a water heat exchanger that exchanges heat between the refrigerant and water, and a combination of the air heat exchanger and the water heat exchanger. a refrigerant circuit having an expansion valve provided therebetween, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path;
a water circuit having a water pipe inserted into the water heat exchanger, a water pump that sends the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe;
a control device that controls the refrigerant circuit and the water circuit;
Equipped with
The control device includes a detection unit that detects an abnormality in the water heat exchanger when a saturation temperature on a low pressure side or a high pressure side of the refrigerant circuit is less than a predetermined lower limit of saturation temperature.
chilling unit. The detection unit of the control device is configured such that during the cooling operation, the saturation temperature on the low pressure side of the refrigerant circuit is less than a first saturation temperature lower limit, and the degree of supercooling at the outlet of the air heat exchanger is a degree of supercooling reference. detecting an abnormality indicating refrigerant leakage in the water heat exchanger when the water temperature at the outlet of the water heat exchanger in the water circuit is equal to or higher than the lower limit of the water temperature control range;
The chilling unit according to claim 1. The detection unit of the control device detects an abnormality indicating a sign of refrigerant leakage in the water heat exchanger when a saturation temperature on the low pressure side of the refrigerant circuit is less than a second lower limit value of saturation temperature during heating operation. To detect,
The chilling unit according to claim 1 or 2. The detection unit of the control device detects a sign of refrigerant leakage in the water heat exchanger when the saturation temperature on the low pressure side or the high pressure side of the refrigerant circuit is less than a third saturation temperature lower limit during an operation stop. detect anomalies that indicate
A chilling unit according to any one of claims 1 to 3. When the control device detects a sign of refrigerant leakage, the control device closes the expansion valve, switches the four-way valve to the flow path for the heating operation, and performs a first process of starting the compressor. further comprising a control unit for executing;
A chilling unit according to any one of claims 2 to 4. After executing the first process, the control unit of the control device stops the compressor when the pressure on the high pressure side of the refrigerant circuit becomes equal to or higher than the pressure upper limit, and causes the pressure on the high pressure side of the refrigerant circuit to increase. further performing a second process of starting the compressor when the pressure becomes less than the lower limit;
The chilling unit according to claim 5. The control unit of the control device sets the pressure lower limit value to a value obtained by adding a predetermined margin to the measured value of the pressure on the inlet side of the water circuit.
The chilling unit according to claim 6. The control unit of the control device further executes a third process of stopping the water pump and closing the water valve when detecting the sign of the refrigerant leak.
A chilling unit according to any one of claims 5 to 7. A compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, a water heat exchanger that exchanges heat between the refrigerant and water, and a combination of the air heat exchanger and the water heat exchanger. a refrigerant circuit having an expansion valve provided therebetween, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path;
a water circuit having a water pipe inserted into the water heat exchanger, a water pump that sends the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe;
a control device that controls the refrigerant circuit and the water circuit;
A method for controlling a chilling unit comprising:
A control method comprising: the control device detecting an abnormality in the water heat exchanger when a saturation temperature on a low pressure side or a high pressure side of the refrigerant circuit is less than a predetermined lower limit value of saturation temperature. A compressor that compresses a refrigerant, an air heat exchanger that exchanges heat between the refrigerant and outside air, a water heat exchanger that exchanges heat between the refrigerant and water, and a combination of the air heat exchanger and the water heat exchanger. a refrigerant circuit having an expansion valve provided therebetween, and a four-way valve that switches the refrigerant flow path to a cooling operation flow path or a heating operation flow path;
a water circuit having a water pipe inserted into the water heat exchanger, a water pump that sends the water to the water pipe, and a water valve provided on the downstream side of the water heat exchanger in the water pipe;
A chilling unit control device comprising:
A program that executes a step of detecting an abnormality in the water heat exchanger when a saturation temperature on a low pressure side or a high pressure side of the refrigerant circuit is less than a predetermined lower limit of saturation temperature.

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