Patent Description:
In a chilling unit, when a heat exchanger (hereinafter also described as a "water heat exchanger") configured to exchange heat between a refrigerant and water is damaged due to, for example, freezing or corrosion due to water quality, the refrigerant may leak from the refrigerant circuit to the water circuit. Patent Document <NUM> describes a technology of detecting refrigerant leakage when concentration of the refrigerant exceeds a reference value for a certain period of time or longer. Document <CIT> discloses a device as per the preamble of claim <NUM>.

If the chilling unit continues to operate in a state where the water heat exchanger is damaged, pressure in the refrigerant circuit and pressure in the water circuit may become equalized. In this case, water may enter the refrigerant circuit. When water enters the refrigerant circuit, each device connected to the refrigerant circuit, including a compressor, an accumulator, a receiver, and valves (e.g., an expansion valve and a four-way valve), in addition to the water heat exchanger, may need to be replaced during repair, and it may cost to repair and take days until restoration. Therefore, an anomaly such as damage to the water heat exchanger is preferably quickly detected such that the damage does not spread.

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

According to one aspect of the present invention, a chilling unit as defined in claim <NUM> is provided.

According to one aspect of the present invention, a control method as defined in claim <NUM> is provided.

According to one aspect of the present disclosure, a program as defined in claim <NUM> is provided.

A chilling unit, a control method, and a program according to the present disclosure can quickly detect an anomaly in a water heat exchanger.

Hereinafter, a chilling unit according to a first embodiment of the present disclosure will be described with reference to <FIG>.

As illustrated in <FIG>, a chilling unit <NUM> includes a refrigerant circuit <NUM>, a water circuit <NUM>, and a control device <NUM>.

The refrigerant circuit <NUM> includes a compressor <NUM>, a four-way valve <NUM>, a water heat exchanger <NUM>, an expansion valve <NUM>, a receiver <NUM>, an air heat exchanger <NUM>, and an accumulator <NUM>. Each device of the refrigerant circuit <NUM> is connected by a refrigerant pipe <NUM>.

The compressor <NUM> compresses a refrigerant R and supplies the compressed refrigerant R to the refrigerant circuit <NUM>.

The four-way valve <NUM> switches between the cooling operation and the heating operation by switching the flow path of the refrigerant circuit <NUM>. As illustrated in <FIG>, the four-way valve <NUM> feeds, to the air heat exchanger <NUM>, the refrigerant R discharged from the compressor <NUM> during the cooling operation. Further, as illustrated in <FIG>, the four-way valve <NUM> feeds, to the water heat exchanger <NUM>, the refrigerant R discharged from the compressor <NUM> during the heating operation.

The water heat exchanger <NUM> cools or heats water W by performing heat exchange between the refrigerant R and the water W.

The expansion valve <NUM> includes a mechanism for reducing pressure of the refrigerant R when the refrigerant R passes through the expansion valve <NUM>. As illustrated in <FIG>, the expansion valve <NUM> includes a first expansion valve <NUM>, a second expansion valve <NUM>, and a third expansion valve <NUM>. The first expansion valve <NUM> is an expansion valve for the cooling operation. The second expansion valve <NUM> and the third expansion valve <NUM> are expansion valves for the heating operation. The second expansion valve <NUM> is provided between the water heat exchanger <NUM> and the receiver <NUM>, and the third expansion valve <NUM> is provided between the receiver <NUM> and the air heat exchanger <NUM>.

As illustrated in <FIG>, during the cooling operation, the first expansion valve <NUM> is in an open state, and the second expansion valve <NUM> and the third expansion valve <NUM> are in a closed state. As illustrated in <FIG>, during the heating operation, the first expansion valve <NUM> is in the closed state, and the second expansion valve <NUM> and the third expansion valve <NUM> are in the open state. Further, as illustrated in <FIG>, during an operation stop, the first expansion valve <NUM> and the third expansion valve <NUM> are in a closed state, and the second expansion valve <NUM> is in an open state.

The receiver <NUM> is a container for storing at least some of a liquid refrigerant that passes through the second expansion valve <NUM> or the third expansion valve <NUM>.

The air heat exchanger <NUM> performs heat exchange between the refrigerant R and outside air taken in by a propeller fan <NUM>.

The accumulator <NUM> is a device that is provided on an upstream side of the compressor <NUM> and separates liquid refrigerant and gas refrigerant. Only the gas refrigerant of the refrigerant separated by the accumulator <NUM> is sent to the compressor <NUM>.

A plurality of sensors for measuring the pressure and temperature of the refrigerant R are provided in the refrigerant circuit <NUM>. A high-pressure-side sensor <NUM> that measures pressure (HP) of the refrigerant R on a high-pressure side is provided in the refrigerant pipe <NUM> between the compressor <NUM> and the four-way valve <NUM> (on a downstream side of the compressor <NUM>). A low-pressure-side sensor <NUM> that measures pressure (LP) of the refrigerant R on a low-pressure side is provided in the refrigerant pipe <NUM> between the accumulator <NUM> and the four-way valve <NUM> (on an upstream side of the accumulator <NUM>). Further, a first temperature sensor <NUM> that measures a temperature of the refrigerant R is provided in the refrigerant pipe <NUM> between the expansion valve <NUM> and the air heat exchanger <NUM>. Measurement values measured by each of the sensors are sequentially transmitted to the control device <NUM>.

The water circuit <NUM> includes a water pipe <NUM>, a water pump <NUM>, and a water valve <NUM>. The water pipe <NUM> is inserted through the water heat exchanger <NUM>. The water pump <NUM> is provided closer to an upstream side of the water pipe <NUM> than the water heat exchanger <NUM>, and sends the water W from the outside to the water pipe <NUM>. While passing through the water heat exchanger <NUM>, the water W sent by the water pump <NUM> undergoes heat exchange with the refrigerant R so that the temperature of the water W is adjusted. The water valve <NUM> is provided closer to a downstream side of the water pipe <NUM> than the water heat exchanger <NUM>. When the water valve <NUM> is opened, the water W after undergoing temperature adjustment is discharged to the outside through the water pipe <NUM>. When the water valve <NUM> is closed, the discharge of the water W to the outside is stopped.

A plurality of sensors for measuring the pressure and temperature of the water W are provided in the water circuit <NUM>. A first water pressure sensor <NUM> that measures pressure (WP1) of the water W on an inlet side of the water heat exchanger <NUM> is provided in the water pipe <NUM> on an upstream side of the water heat exchanger <NUM>. A second water pressure sensor <NUM> that measures pressure (WP2) of the water W on an outlet side of the water heat exchanger <NUM> is provided in the water pipe <NUM> on a downstream side of the water heat exchanger <NUM>. Further, a second temperature sensor <NUM> that measures a temperature of the water W is provided in the water pipe <NUM> on the downstream side (near the outlet) of the water heat exchanger <NUM>. Measurement values measured by each of the sensors are sequentially transmitted to the control device <NUM>.

The control device <NUM> controls the operation of each device of the refrigerant circuit <NUM> and the water circuit <NUM>, and brings the chilling unit <NUM> into any state of the cooling operation, the heating operation, and the operation stop.

The control device <NUM> according to the present embodiment detects an anomaly in the water heat exchanger <NUM> on the basis of a measurement value received from each of the sensors of the refrigerant circuit <NUM> and the water circuit <NUM>. Further, the control device <NUM> performs processing of suppressing entry of the water W into the refrigerant circuit <NUM> when a sign of leakage of the refrigerant R is detected in the water heat exchanger <NUM>. The details of this processing will be described later.

<FIG> is a diagram illustrating a functional configuration of the control device according to the first embodiment of the present disclosure.

As illustrated in <FIG>, the control device <NUM> includes a processor <NUM>, a main memory <NUM>, a storage <NUM>, an interface <NUM>, and a display unit <NUM>.

The processor <NUM> operates according to a predetermined program to function as a detecting unit <NUM>, a control unit <NUM>, and an alarm unit <NUM>.

The detecting unit <NUM> detects an anomaly in the water heat exchanger <NUM>, based on a measurement value of each of the sensors provided in the refrigerant circuit <NUM> and the water circuit <NUM>. Specifically, the detecting unit <NUM> detects a low-pressure anomaly in the water heat exchanger <NUM> when a saturation temperature of the refrigerant R is less than a predetermined saturation temperature lower limit value. The detecting unit <NUM> further detects presence or absence of a sign of leakage of the refrigerant R from the water heat exchanger <NUM> during each of the cooling operation, the heating operation, and the operation stop.

In a case where a sign of leakage of the refrigerant R from the water heat exchanger <NUM> is detected, the control unit <NUM> performs various types of processing for suppressing entry of the water W into the refrigerant circuit <NUM>.

In a case where an anomaly in the water heat exchanger <NUM> is detected, the alarm unit <NUM> issues an anomaly alarm via the display unit <NUM>. Note that the alarm unit <NUM> may issue an anomaly alarm to an external monitoring device (e.g., a computer, a smartphone, or a tablet) via the interface <NUM>.

Commands and data for the processor <NUM> to operate based on a program are deployed to the main memory <NUM>.

The storage <NUM> is a so-called auxiliary storage device, and may be, for example, an electrically erasable programmable read-only memory (EEPROM), a hard disk drive (HDD), or a solid state drive (SSD).

The interface <NUM> is an interface (communication interface) for communicably connecting each device and sensor in the refrigerant circuit <NUM> and the water circuit <NUM>.

The display unit <NUM> is a display that displays information such as the presence or absence of an anomaly in the chilling unit <NUM>.

<FIG> is a flowchart illustrating an example of processing of the control device according to the first embodiment of the present disclosure during the cooling operation.

Hereinafter, a flow of processing of monitoring an anomaly in the water heat exchanger <NUM> during a cooling operation and processing at the time of an anomaly will be described with reference to <FIG>.

The control unit <NUM> controls the operating state of each device of the refrigerant circuit <NUM> and the water circuit <NUM> to perform the cooling operation of the chilling unit <NUM> (step S100). For example, as illustrated in <FIG>, the control unit <NUM> switches the four-way valve <NUM> such that the refrigerant R discharged by the compressor <NUM> flows into the air heat exchanger <NUM>, and also brings the first expansion valve <NUM> into the open state and brings the second expansion valve <NUM> and the third expansion valve <NUM> into the closed state. Then, when the compressor <NUM> is operated, the four-way valve <NUM> switches to serve as a refrigerant circuit for the cooling operation. Before the control unit <NUM> operates the compressor <NUM>, the control unit <NUM> operates the water pump <NUM> in the water circuit <NUM>, and also brings the water valve <NUM> into the open state if the water valve <NUM> is installed. In this way, the water W flowing through the water circuit <NUM> is cooled by the refrigerant R while passing through the water heat exchanger <NUM>.

Further, the detecting unit <NUM> constantly monitors a measurement value (pressure LP of the refrigerant R on the low-pressure side) of the low-pressure-side sensor <NUM> of the refrigerant circuit <NUM> during the cooling operation to detect presence or absence of a pressure anomaly of the refrigerant. In the present embodiment, each time the detecting unit <NUM> receives a measurement value from the low-pressure-side sensor <NUM>, the detecting unit <NUM> monitors whether a saturation temperature on the low-pressure side (hereinafter also described as an "LP saturation temperature") is less than a first saturation temperature lower limit value (e.g., -A°C) (step S101). For example, a correspondence table of saturation pressure and saturation temperature for each type of the refrigerant R is previously recorded in the storage <NUM>, and the detecting unit <NUM> determines the LP saturation temperature with reference to the correspondence table. Further, the first saturation temperature lower limit value is preset according to the type of the refrigerant R or the like.

In a case where the LP saturation temperature is equal to or greater than the first saturation temperature lower limit value (step S101: NO), the detecting unit <NUM> determines that there is no anomaly in the pressure state of the refrigerant. In this case, the control device <NUM> continues the cooling operation of the chilling unit <NUM>.

On the other hand, in a case where the LP saturation temperature is less than the first saturation temperature lower limit value (step S101: YES), the detecting unit <NUM> detects that an anomaly has occurred in low pressure of the refrigerant. In this case, the control unit <NUM> stops the cooling operation of the chilling unit <NUM>. Further, the alarm unit <NUM> issues an anomaly alarm indicating an anomaly in the refrigerant circuit <NUM> (step S102). At this time, the alarm unit <NUM> may display a value of the LP saturation temperature or the like together with the anomaly alarm on the display unit <NUM>. Further, the alarm unit <NUM> may issue the anomaly alarm to an external monitoring terminal or the like via the interface <NUM>. When the low-pressure anomaly alarm for the refrigerant is issued, an administrator of the chilling unit <NUM> arranges for repair of the chilling unit <NUM>.

Next, the detecting unit <NUM> confirms presence or absence of a sign of leakage of the refrigerant R into the water circuit <NUM> in the water heat exchanger <NUM>. Specifically, first, the detecting unit <NUM> determines a subcooling degree at an outlet of the air heat exchanger <NUM>, based on a measurement value of the first temperature sensor <NUM> immediately before the low-pressure anomaly occurs. Note that, in other embodiments, the first temperature sensor <NUM> may be a sensor that can measure a subcooling degree, and the detecting unit <NUM> may acquire the subcooling degree at the outlet of the air heat exchanger <NUM> from the first temperature sensor <NUM>. Then, the detecting unit <NUM> determines whether the subcooling degree at the outlet of the air heat exchanger <NUM> is significantly lower than a predetermined subcooling degree reference value, and whether subcooling cannot be guaranteed (step S <NUM>). Note that the subcooling degree reference value is preset according to the type of the refrigerant R or the like.

In a case where the subcooling degree at the outlet of the air heat exchanger <NUM> is not lower than the subcooling degree reference value (step S <NUM>: NO), the detecting unit <NUM> determines that there is no sign of leakage of the refrigerant R (step S <NUM>). In this case, the control unit <NUM> terminates the processing while the operation of the chilling unit <NUM> is stopped.

On the other hand, in a case where the subcooling degree at the outlet of the air heat exchanger <NUM> is lower than the subcooling degree reference value (step S <NUM>: YES), the detecting unit <NUM> further confirms whether a water temperature at the outlet of the water heat exchanger <NUM> of the water circuit <NUM> immediately before the low-pressure anomaly occurs is less than a lower limit value (e.g., <NUM>) in a water temperature control range (step S <NUM>). The lower limit value in the water temperature control range indicates a set temperature in a settable temperature range in the chilling unit <NUM>. For example, in a case where the settable temperature range is "from <NUM> to <NUM>", the lower limit value is "<NUM>" when the set temperature is "<NUM>", and the lower limit value is "<NUM>" when the set temperature is "<NUM>".

When there is no refrigerant leakage at the time of a low-temperature anomaly (the amount of the refrigerant R is sufficient in the refrigerant circuit <NUM>), the water temperature decreases (reaches a subcooling temperature) as the pressure LP on the low-pressure side decreases. Thus, in a case where the water temperature at the outlet of the water heat exchanger <NUM> measured by the second temperature sensor <NUM> is less than the lower limit value in the water temperature control range (step S104: NO), the detecting unit <NUM> determines that there is no sign of leakage of the refrigerant R (step S <NUM>). In other words, the low-pressure anomaly of the refrigerant is determined to be due to a cause other than refrigerant leakage from the water heat exchanger <NUM>, for example, clogging of the refrigerant circuit <NUM>. In this case, the control unit <NUM> terminates the processing while the operation of the chilling unit <NUM> is stopped.

On the other hand, in a case where there is refrigerant leakage at the time of the low-pressure anomaly, the amount of the refrigerant R is insufficient, and thus it is difficult to sufficiently perform cooling until the lower limit value (set temperature) is reached. Thus, in a case where the water temperature at the outlet of the water heat exchanger <NUM> is equal to or greater than the lower limit value in the water temperature control range (step S104: YES), the detecting unit <NUM> determines that leakage has already occurred in the water heat exchanger <NUM>, and the refrigerant and water are mixed and the water temperature cannot be controlled. In this case, the alarm unit <NUM> issues an anomaly alarm indicating the refrigerant leakage in the water heat exchanger <NUM> (step S <NUM>). When the anomaly alarm indicating the refrigerant leakage from the water heat exchanger <NUM> is issued, an administrator of the chilling unit <NUM> arranges for repair of the chilling unit <NUM>.

The refrigerant circuit <NUM> normally has a pressure higher than that of the water circuit <NUM>. However, when leakage of the refrigerant R advances and pressure in the refrigerant circuit <NUM> and pressure in the water circuit <NUM> are equalized, the water W of the water circuit <NUM> may enter the refrigerant circuit <NUM>. In addition, it may take a long time from when repair is arranged to when repair of the chilling unit <NUM> is actually performed. Therefore, when the leakage of the refrigerant R is left until the repair of the chilling unit <NUM> is performed, the water W enters the refrigerant circuit <NUM>, and damage to the chilling unit <NUM>, such as failure of the compressor <NUM>, may spread.

In order to reduce the likelihood of such damage to the chilling unit <NUM> spreading, the control unit <NUM> according to the present embodiment performs automatic processing of suppressing entry of the water W into the refrigerant circuit <NUM> when the refrigerant leakage is detected. Details of this processing will be described with reference to <FIG> and <FIG>.

<FIG> is a diagram illustrating an example of a control state when refrigerant leakage in the chilling unit according to the first embodiment of the present disclosure is detected.

First, processing in the water circuit <NUM> will be described. In a case where the water heat exchanger <NUM> is damaged, when the water W flows on the water circuit <NUM> side, the water W may leak into the refrigerant circuit <NUM>. Thus, as illustrated in <FIG>, the control unit <NUM> performs third processing of stopping the water pump <NUM> of the water circuit <NUM> and bringing the water valve <NUM> into the closed state (step S107). In this way, entry of the water W into the refrigerant circuit <NUM> can be suppressed. Further, in a system in which a plurality of the chilling units <NUM> are coupled with one water circuit <NUM>, when the refrigerant R leaks into the water circuit <NUM> of a certain chilling unit <NUM>, the water W mixed with the refrigerant R can be prevented from circulating in another chilling unit.

Further, processing in the refrigerant circuit <NUM> will be described. The control unit <NUM> performs first processing (steps S108 and S109) of increasing pressure in the refrigerant circuit <NUM> such that the pressure in the refrigerant circuit <NUM> is not equalized with the pressure in the water circuit <NUM>. Specifically, as illustrated in <FIG>, the control unit <NUM> brings the first expansion valve <NUM> and the second expansion valve <NUM> into the closed state, brings the third expansion valve <NUM> into the open state, and also operates the four-way valve <NUM> to switch to a heating operation flow path (step S108). Further, the control unit <NUM> starts up the compressor <NUM> (step S109). In this way, the control unit <NUM> sends the refrigerant R compressed by the compressor <NUM> while limiting the flow path on a downstream side of the compressor <NUM> to a short section ending at the second expansion valve <NUM>, and thus increases pressure in the section from the compressor <NUM> to the second expansion valve <NUM> in the refrigerant circuit <NUM>, that is, a section around the water heat exchanger <NUM>.

Furthermore, the control unit <NUM> performs second processing (steps S110 to S <NUM>) of maintaining the pressure in the section around the water heat exchanger <NUM> in the refrigerant circuit <NUM> within a fixed range.

First, the control unit <NUM> confirms whether the high-pressure-side pressure HP of the refrigerant circuit <NUM> measured by the high-pressure-side sensor <NUM> after the compressor <NUM> starts up exceeds a pressure upper limit value (step S <NUM>). The pressure upper limit value is, for example, a value acquired by adding a predetermined margin α1 to the inlet-side pressure WP1 of the water circuit <NUM> measured by the first water pressure sensor <NUM>. The value of the margin α1 is preset according to the type of the refrigerant R, a characteristic of the compressor <NUM>, or the like.

In a case where the high-pressure-side pressure HP is equal to or less than the pressure upper limit value (step S <NUM>: NO), the control unit <NUM> continues the operation of the compressor <NUM>.

On the other hand, in a case where the high-pressure-side pressure HP exceeds the pressure upper limit value (step S110: YES), the control unit <NUM> stops the compressor <NUM> (step Sill). In this way, the control unit <NUM> can suppress an increase more than necessary in the pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> with respect to the pressure in the water circuit <NUM>.

Further, after the control unit <NUM> stops the compressor <NUM>, the control unit <NUM> confirms whether the high-pressure-side pressure HP is less than the pressure lower limit value (step S112). The pressure upper limit value is, for example, a value acquired by adding a predetermined margin α2 to the inlet-side pressure WP1 of the water circuit <NUM> measured by the first water pressure sensor <NUM>. The value of the margin α2 is preset according to the type of the refrigerant R, a characteristic of the compressor <NUM>, or the like. Note that the values of the margins α1 and α2 may be the same, or may be different.

In a case where the high-pressure-side pressure HP is equal to or greater than the pressure lower limit value (step S <NUM>: NO), the control unit <NUM> causes the compressor <NUM> to remain stopped.

On the other hand, in a case where the high-pressure-side pressure HP is less than the pressure lower limit value (step S112: YES), the control unit <NUM> starts up the compressor <NUM> (returns to step S109). In this way, the control unit <NUM> can suppress entry of the water W into the refrigerant circuit <NUM> because the pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> is equalized with the pressure in the water circuit <NUM>.

In this way, when a sign of leakage of the refrigerant R is detected during the cooling operation, the control unit <NUM> performs the first to third processing as illustrated in <FIG>, and suppresses entry of the water W in the water circuit <NUM> into the refrigerant circuit <NUM> to prevent the spread of damage in the chilling unit <NUM>.

<FIG> is a flowchart illustrating an example of processing of the control device according to the first embodiment of the present disclosure during the heating operation.

Hereinafter, a flow of processing of monitoring an anomaly in the water heat exchanger <NUM> during the heating operation and processing at the time of the anomaly will be described with reference to <FIG>.

The control unit <NUM> controls the operation state of each device of the refrigerant circuit <NUM> and the water circuit <NUM>, and performs the heating operation of the chilling unit <NUM> (step S200). For example, as illustrated in <FIG>, the control unit <NUM> switches the four-way valve <NUM> such that the refrigerant R discharged by the compressor <NUM> flows into the water heat exchanger <NUM>, and also brings the first expansion valve <NUM> into the closed state and brings the second expansion valve <NUM> and the third expansion valve <NUM> into the open state. When the control unit <NUM> switches the refrigerant circuit <NUM> to a heating operation flow path in such a manner, the control unit <NUM> operates the compressor <NUM>. Before the control unit <NUM> operates the compressor <NUM>, the control unit <NUM> operates the water pump <NUM> in the water circuit <NUM>, and also brings the water valve <NUM> into the open state if the water valve <NUM> is installed. In this way, the water W flowing through the water circuit <NUM> is heated by the refrigerant R while passing through the water heat exchanger <NUM>.

Further, the detecting unit <NUM> constantly monitors the pressure LP of the refrigerant R on the low-pressure side during the heating operation to detect presence or absence of an anomaly in the water heat exchanger <NUM>. Specifically, the detecting unit <NUM> monitors whether an outside temperature is equal to or greater than <NUM> and whether the LP saturation temperature is less than a second saturation temperature lower limit value (e.g., -B°C) (step S201). Note that the second saturation temperature lower limit value is preset according to the type of the refrigerant R or the like.

In a case where the outside temperature is less than <NUM> or the LP saturation temperature is equal to or greater than the second saturation temperature lower limit value (step S201: NO), the detecting unit <NUM> determines that there is no anomaly (no leakage) in the refrigerant circuit <NUM>. In this case, the control device <NUM> continues the heating operation of the chilling unit <NUM>.

On the other hand, in a case where the outside temperature is equal to or greater than <NUM> and the LP saturation temperature is less than the second saturation temperature lower limit value (step S201: YES), the detecting unit <NUM> detects that leakage from the refrigerant circuit <NUM> may occur and there may be a sign of leakage of the refrigerant R in the water heat exchanger <NUM>. In this case, the control unit <NUM> stops the heating operation of the chilling unit <NUM>. Further, the alarm unit <NUM> issues an anomaly alarm indicating the sign of refrigerant leakage in the water heat exchanger <NUM> (step S202).

When the sign of refrigerant leakage is detected, the control unit <NUM> performs processing of suppressing entry of the water W into the refrigerant circuit <NUM> similarly to the cooling operation.

For the water circuit <NUM>, the control unit <NUM> performs third processing of stopping the water pump <NUM> of the water circuit <NUM> and bringing the water valve <NUM> into the closed state (step S203). This processing is the same as that in step S107 in <FIG>.

For the refrigerant circuit <NUM>, first, the control unit <NUM> performs first processing (steps S204 and S205) of increasing pressure in the refrigerant circuit <NUM> such that the pressure in the refrigerant circuit <NUM> is not equalized with pressure in the water circuit <NUM>. When the heating operation is stopped in step S202, the flow path may switch to the flow path during the operation stop illustrated in <FIG>. Thus, as illustrated in <FIG>, the control unit <NUM> brings the first expansion valve <NUM> and the second expansion valve <NUM> into the closed state, brings the third expansion valve <NUM> into the open state, and also operates the four-way valve <NUM> to switch to the heating operation flow path (step S204). Further, the control unit <NUM> starts up the compressor <NUM> (step S205), and increases pressure in the section from the compressor <NUM> to the second expansion valve <NUM> in the refrigerant circuit <NUM>, that is, the section around the water heat exchanger <NUM>. This processing is the same as that in steps S108 to S109 in <FIG>.

Furthermore, the control unit <NUM> performs second processing (steps S206 to S208) of maintaining the pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> within a fixed range. This processing is the same as that in steps S110 to S112 in <FIG>.

When a sign of leakage of the refrigerant R is detected during the heating operation, the control unit <NUM> performs the first to third processing as illustrated in <FIG>, and suppresses a decrease in the pressure in the refrigerant circuit <NUM> and entry of the water W in the water circuit <NUM> into the refrigerant circuit <NUM>.

<FIG> is a flowchart illustrating an example of processing of the control device according to the first embodiment of the present disclosure during the operation stop.

Hereinafter, a flow of processing of monitoring an anomaly in the water heat exchanger <NUM> during the operation stop and processing at the time of the anomaly will be described with reference to <FIG>.

The control unit <NUM> brings the chilling unit <NUM> into a state of operation stop according to an operation by an administrator or the like of the chilling unit <NUM> (step S300). At this time, as illustrated in <FIG>, the control unit <NUM> brings the first expansion valve <NUM> and the third expansion valve <NUM> into the closed state and brings the second expansion valve <NUM> into the open state to stop the compressor <NUM>. Further, the control unit <NUM> stops the water pump <NUM> and brings the water valve <NUM> into the closed state. Note that, in other embodiments, for protection control, the control unit <NUM> may operate the water pump <NUM> and bring the water valve <NUM> into the open state even during the operation stop.

Further, the detecting unit <NUM> constantly monitors the low-pressure-side pressure LP or the high-pressure-side pressure HP of the refrigerant R during the operation stop to detect presence or absence of an anomaly in the water heat exchanger <NUM>. Specifically, the detecting unit <NUM> monitors whether an outside temperature is equal to or greater than <NUM> and whether the LP saturation temperature or a saturation temperature on the high-pressure side (hereinafter also described as an "HP saturation temperature") is less than a third saturation temperature lower limit value (e.g., -C°C) (step S301). Note that the third saturation temperature lower limit value is preset according to the type of the refrigerant R or the like.

In a case where the outside temperature is less than <NUM>, or the LP saturation temperature or the HP saturation temperature is equal to or greater than the third saturation temperature lower limit value (step S301: NO), the detecting unit <NUM> determines that there is no problem in the refrigerant circuit <NUM> and there is no anomaly in the water heat exchanger <NUM>. In this case, the control device <NUM> causes the chilling unit <NUM> to remain in the state of the operation stop.

On the other hand, in a case where the outside temperature is equal to or greater than <NUM>, and the LP saturation temperature or the HP saturation temperature is less than the third saturation temperature lower limit value (step S301: YES), the detecting unit <NUM> detects that leakage from the refrigerant circuit <NUM> may occur and there may be a sign of leakage of the refrigerant R in the water heat exchanger <NUM>. In this case, the alarm unit <NUM> issues an anomaly alarm indicating a sign of the refrigerant leakage from the refrigerant circuit <NUM> (step S302).

In a case of operation of operating the water pump <NUM> even during the operation stop, the control unit <NUM> performs third processing of stopping the water pump <NUM> of the water circuit <NUM>, and also bringing the water valve <NUM> into the closed state (step S303). This processing is the same as that in step S107 in <FIG>. Note that, in a case of an operation of stopping the water pump <NUM> during the operation stop, step S303 may be omitted.

For the refrigerant circuit <NUM>, first, the control unit <NUM> performs first processing (steps S304 and S305) of increasing pressure in the refrigerant circuit <NUM> such that the pressure in the refrigerant circuit <NUM> is not equalized with pressure in the water circuit <NUM>. This processing is the same as that in steps S108 to S109 in <FIG>.

Furthermore, the control unit <NUM> performs second processing (steps S306 to S308) of maintaining the pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> within a fixed range. This processing is the same as that in steps S110 to S112 in <FIG>.

When a sign of leakage of the refrigerant R is detected during the operation stop, the control unit <NUM> performs the first to third processing as illustrated in <FIG>, and suppresses a decrease in the pressure in the refrigerant circuit <NUM> and entry of the water W in the water circuit <NUM> into the refrigerant circuit <NUM>.

Note that, in step S301 in <FIG>, when the outside temperature is equal to or greater than <NUM>, and the LP saturation temperature or the HP saturation temperature is less than the third saturation temperature lower limit value (when a first condition is satisfied), the detecting unit <NUM> according to the present embodiment detects that a sign of leakage of the refrigerant R has occurred, and, in steps S303 to S308, the detecting unit <NUM> assumes leakage from the water heat exchanger <NUM> and performs maintenance control, which is not limited thereto. In other embodiments, when another condition (second condition) is satisfied in step S301 instead of the first condition or in addition to the first condition, the detecting unit <NUM> may detect that a sign of leakage of the refrigerant R has occurred in the water heat exchanger <NUM>. A case in which the second condition is satisfied is, for example, a case in which the outside temperature is equal to or greater than <NUM> and a difference between the LP saturation temperature (or the HP saturation temperature) and the outside temperature is equal to or greater than a predetermined temperature differential (e.g., <NUM> degrees), and a change in the LP saturation temperature (or the HP saturation temperature) does not follow a temperature change of the outside temperature. The detecting unit <NUM> can detect the refrigerant leakage of the refrigerant R by confirming whether the second condition is satisfied.

Note that <FIG>, <FIG>, and <FIG> illustrate an example in which the control unit <NUM> performs the first processing (steps S108 and S109, S204 and S205, and S304 and S305) after the third processing (steps S <NUM>, S203, and S303), but the order of the processing is not limited thereto. The control unit <NUM> may perform the third processing after the first processing or simultaneously with the first processing.

As described above, in the chilling unit <NUM> according to the present embodiment, the control device <NUM> includes the detecting unit <NUM> configured to detect an anomaly in the water heat exchanger <NUM> when an LP saturation temperature or an HP saturation temperature of the refrigerant circuit <NUM> is less than a predetermined saturation temperature lower limit value.

With this configuration, the chilling unit <NUM> can quickly detect an anomaly in the water heat exchanger <NUM>.

Further, the detecting unit <NUM> of the control device <NUM> detects an anomaly indicating refrigerant leakage in the water heat exchanger <NUM> when, during a cooling operation, the LP saturation temperature of the refrigerant circuit <NUM> is less than a first saturation temperature lower limit value, a subcooling degree at an outlet of the air heat exchanger <NUM> is lower than a subcooling degree reference value, and a water temperature at an outlet of the water heat exchanger <NUM> of the water circuit <NUM> is equal to or greater than a lower limit value in a water temperature control range.

With this configuration, the chilling unit <NUM> can quickly detect refrigerant leakage during the cooling operation.

Further, the detecting unit <NUM> of the control device <NUM> detects an anomaly indicating a sign of refrigerant leakage in the water heat exchanger <NUM> when the LP saturation temperature of the refrigerant circuit <NUM> is less than a second saturation temperature lower limit value during a heating operation.

With this configuration, the chilling unit <NUM> can quickly detect a sign of refrigerant leakage during the heating operation.

Further, the detecting unit <NUM> of the control device <NUM> detects an anomaly indicating a sign of refrigerant leakage in the water heat exchanger <NUM> when the LP saturation temperature or the HP saturation temperature of the refrigerant circuit <NUM> is less than a third saturation temperature lower limit value during an operation stop.

With this configuration, the chilling unit <NUM> can quickly detect a sign of refrigerant leakage during the operation stop.

In addition, the control device <NUM> further includes the control unit <NUM> that performs first processing of closing the first expansion valve <NUM> and the second expansion valve <NUM>, switching the four-way valve <NUM> so as to set the heating operation flow path, and starting up the compressor <NUM> when a sign of the refrigerant leakage is detected.

With this configuration, for a period until the water heat exchanger <NUM> is repaired or replaced, the chilling unit <NUM> can maintain a state where the refrigerant circuit <NUM> has pressure greater than that of the water circuit <NUM>, and can suppress entry of the water W into the refrigerant circuit <NUM>. In this way, the likelihood of each device connected to the refrigerant circuit <NUM> being damaged by the water that enters the refrigerant circuit <NUM> can be reduced.

In addition, the control unit <NUM> of the control device <NUM> further performs second processing of, after the first processing is performed, stopping the compressor <NUM> when the high-pressure-side pressure HP of the refrigerant circuit <NUM> is equal to or greater than a pressure upper limit value, and starting up the compressor <NUM> when the high-pressure-side pressure HP of the refrigerant circuit <NUM> is less than a pressure lower limit value.

With this configuration, the chilling unit <NUM> can maintain pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> within a fixed range. In this way, entry of the water W from the water circuit <NUM> into the refrigerant circuit <NUM> can be suppressed.

Further, the control unit <NUM> of the control device <NUM> sets, as the pressure lower limit value, a value acquired by adding the predetermined margin α2 to the inlet-side pressure WP1 of the water circuit <NUM>.

With this configuration, the chilling unit <NUM> can maintain pressure in the section around the water heat exchanger <NUM> of the refrigerant circuit <NUM> in a state of being higher than pressure in the water circuit <NUM>. In this way, entry of the water W from the water circuit <NUM> into the refrigerant circuit <NUM> can be more reliably suppressed.

Further, the control unit <NUM> of the control device <NUM> further performs third processing of stopping the water pump <NUM> and closing the water valve <NUM> when a sign of the refrigerant leakage is detected.

With this configuration, flow of the water W in the water circuit <NUM> can be reliably stopped, and thus entry of the water W into the refrigerant circuit <NUM> can be suppressed. Further, in a system in which a plurality of the chilling units <NUM> are coupled with one water circuit <NUM>, when the refrigerant R leaks into the water circuit <NUM> of a certain chilling unit <NUM>, circulation of the water W mixed with the refrigerant R in another chilling unit can be suppressed.

In the foregoing, certain embodiments of the present disclosure have been described, but all of these embodiments are merely illustrative and are not intended to limit the scope of the invention. These embodiments may be implemented in various other forms, and various omissions, substitutions, and alterations may be made without departing from the invention. These embodiments and modifications are included in the scope of the invention and are also included in the scope of the invention described in the claims and equivalents thereof.

Claim 1:
A chilling unit (<NUM>) comprising:
a refrigerant circuit (<NUM>) including a compressor (<NUM>) configured to compress a refrigerant, an air heat exchanger (<NUM>) configured to perform heat exchange between the refrigerant and outside air, a water heat exchanger (<NUM>) configured to perform heat exchange between the refrigerant and water, an expansion valve (<NUM>) provided between the air heat exchanger (<NUM>) and the water heat exchanger (<NUM>), and a four-way valve (<NUM>) configured to switch a flow path of the refrigerant to a cooling operation flow path or a heating operation flow path;
a water circuit (<NUM>) including a water pipe (<NUM>) inserted through the water heat exchanger (<NUM>), a water pump (<NUM>) configured to send the water to the water pipe (<NUM>), and a water valve (<NUM>) provided closer to a downstream side of the water pipe (<NUM>) than the water heat exchanger (<NUM>); and
a control device (<NUM>) configured to control the refrigerant circuit (<NUM>) and the water circuit (<NUM>), characterised in that
the control device (<NUM>) includes a detecting unit (<NUM>) configured to detect an anomaly in the water heat exchanger (<NUM>) when a saturation temperature of the refrigerant circuit (<NUM>) on a low-pressure side or a high-pressure side is less than a predetermined saturation temperature lower limit value, wherein
the detecting unit (<NUM>) of the control device (<NUM>) is configured to detect an anomaly indicating refrigerant leakage in the water heat exchanger (<NUM>) when, during a cooling operation, a saturation temperature of the refrigerant circuit (<NUM>) on a low-pressure side is less than a first saturation temperature lower limit value, a subcooling degree at an outlet of the air heat exchanger (<NUM>) is lower than a subcooling degree reference value, and a water temperature at an outlet of the water heat exchanger (<NUM>) in the water circuit (<NUM>) is equal to or greater than a lower limit value in a water temperature control range.