Chilling unit, control method, and program

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

Technical Field

[0001] The present disclosure relates to a chilling unit, a control method, and a program.

Background Art

[0002] In a chilling unit, when a heat exchanger between a refrigerant and water (hereinafter also referred to as "water heat exchanger") is damaged due to freezing, corrosion caused by water quality, etc., the refrigerant may leak from the refrigerant circuit to the water circuit. Patent Document 1 describes that refrigerant leakage is detected when the concentration of the refrigerant exceeds a reference value for a certain period of time or more.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] If the operation of the chilling unit is continued in a state where the water heat exchanger is damaged, water may enter the refrigerant circuit when the refrigerant circuit and the water circuit reach equal pressure. When water enters the refrigerant circuit, not only the water heat exchanger but also each device including a compressor, an accumulator, a receiver, and valves (expansion valve, four-way valve, etc.) connected to the refrigerant circuit need to be replaced during repair, which may result in high repair costs and a long time to recovery. Therefore, it is desired to quickly detect an abnormality such as damage to the water heat exchanger so that the damage does not spread.

[0005] The present disclosure has been made in view of such problems, and provides a chilling unit, a control method, and a program capable of quickly detecting an abnormality of a water heat exchanger.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, the chilling unit comprises a refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant between a flow path for cooling operation and a flow path for heating operation; a water circuit having a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe; and a control device for controlling the refrigerant circuit and the water circuit, wherein the control device has a detection unit for detecting an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature.

[0007] According to one aspect of the present disclosure, a control method is a chilling unit control method comprising: a refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for performing heat exchange between the refrigerant and outside air, a water heat exchanger for performing heat exchange between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant to a flow path for cooling operation or a flow path for heating operation; a water circuit having a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe; and a control device for controlling the refrigerant circuit and the water circuit, wherein the control device detects an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature.

[0008] According to one aspect of the present disclosure, the program causes a control device for a chilling unit, which comprises a refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant to a flow path for cooling operation or a flow path for heating operation, and a water circuit having a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe, to execute a step of detecting an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature. [Effects of the Invention]

[0009] According to the chilling unit, control method, and program described herein, abnormalities in the water heat exchanger can be detected quickly. [Brief explanation of the drawing]

[0010] [Figure 1] This is a first figure showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state during cooling operation. [Figure 2] This is a second figure showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state during heating operation. [Figure 3] This is a third figure showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state when the unit is stopped. [Figure 4] This figure shows the functional configuration of the control device according to the first embodiment of this disclosure. [Figure 5] This flowchart shows an example of processing during cooling operation of a control device according to the first embodiment of this disclosure. [Figure 6] This figure shows an example of the control state when a refrigerant leak is detected in a chilling unit according to the first embodiment of this disclosure. [Figure 7]This flowchart shows an example of the processing during heating operation of the control device according to the first embodiment of this disclosure. [Figure 8] This flowchart shows an example of the process when the control device according to the first embodiment of this disclosure is stopped. [Modes for carrying out the invention]

[0011] <First Embodiment> Hereinafter, a chilling unit according to the first embodiment of this disclosure will be described with reference to Figures 1 to 8.

[0012] (Overall configuration of the chilling unit) Figure 1 is a first diagram showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state during cooling operation. Figure 2 is a second diagram showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state during heating operation. Figure 3 is a third diagram showing the configuration of a chilling unit according to the first embodiment of the present disclosure, and is a diagram showing an example of the control state when the unit is stopped. As shown in Figures 1 to 3, the chilling unit 1 consists of a refrigerant circuit 2, a water circuit 3, and a control device 4.

[0013] 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 component of the refrigerant circuit 2 is connected by refrigerant piping 20.

[0014] The compressor 21 compresses the refrigerant R and supplies the compressed refrigerant R to the refrigerant circuit 2.

[0015] The four-way valve 22 switches between the cooling operation and the heating operation by switching the flow path of the refrigerant circuit 2. As shown in FIG. 1, in the cooling operation, the four-way valve 22 directs the refrigerant R discharged from the compressor 21 to the air heat exchanger 26. Also, as shown in FIG. 2, in the heating operation, the four-way valve 22 directs the refrigerant R discharged from the compressor 21 to the water heat exchanger 23.

[0016] The water heat exchanger 23 cools or heats the water W by performing heat exchange between the refrigerant R and the water W.

[0017] The expansion valve 24 has a mechanism for reducing the pressure of the refrigerant R when the refrigerant R passes through. As shown in FIG. 1, the expansion valve 24 has 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. Also, 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.

[0018] 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. Also, when the operation is stopped, as shown in FIG. 3, the first expansion valve 241 and the third expansion valve 243 are in the closed state, and the second expansion valve 242 is in the open state.

[0019] The receiver 25 is a container for storing at least a part of the liquid refrigerant that has passed through the second expansion valve 242 or the third expansion valve 243.

[0020] The air heat exchanger 26 performs heat exchange between the refrigerant R and the outside air taken in by the propeller fan 261.

[0021] The accumulator 27 is located upstream of the compressor 21 and is a device that separates liquid refrigerant from gaseous refrigerant. Of the refrigerant separated by the accumulator 27, only the gaseous refrigerant is sent to the compressor 21.

[0022] Furthermore, the refrigerant circuit 2 is equipped with multiple sensors for measuring the pressure and temperature of the refrigerant R. A high-pressure sensor 201 is provided in the refrigerant piping 20 between the compressor 21 and the four-way valve 22 (downstream of the compressor 21) to measure the high-pressure side pressure (HP) of the refrigerant R. A low-pressure sensor 202 is provided in the refrigerant piping 20 between the accumulator 27 and the four-way valve 22 (upstream of the accumulator 27) to measure the low-pressure side pressure (LP) of the refrigerant R. In addition, a first temperature sensor 203 is provided in the refrigerant piping 20 between the expansion valve 24 and the air heat exchanger 26 to measure the temperature of the refrigerant R. The measured values ​​from each sensor are transmitted sequentially to the control device 4.

[0023] 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 located upstream of the water heat exchanger 23 in the water pipe 30 and sends water W from the outside into the water pipe 30. As the water W sent by the water pump 31 passes through the water heat exchanger 23, it exchanges heat with the refrigerant R and its temperature is adjusted. The water valve 32 is located downstream of the water heat exchanger 23 in the water pipe 30. When the water valve 32 is open, the water W, after temperature adjustment, is discharged to the outside through the water pipe 30. When the water valve 32 is closed, the discharge of water W to the outside is stopped.

[0024] Furthermore, the water circuit 3 is equipped with multiple sensors for measuring the pressure and temperature of the water W. A first water pressure sensor 301 is provided in the water piping 30 upstream of the water heat exchanger 23 to measure the pressure (WP1) of the water W at the inlet side of the water heat exchanger 23. A second water pressure sensor 302 is provided in the water piping 30 downstream of the water heat exchanger 23 to measure the pressure (WP2) of the water W at the outlet side of the water heat exchanger 23. In addition, a second temperature sensor 303 is provided in the water piping 30 downstream of the water heat exchanger 23 (near the outlet) to measure the temperature of the water W. The measured values ​​from each sensor are transmitted sequentially to the control device 4.

[0025] The control device 4 controls the operation of each component in the refrigerant circuit 2 and the water circuit 3 to put the chilling unit 1 into one of three states: cooling operation, heating operation, or shutdown.

[0026] Furthermore, the control device 4 according to this embodiment detects abnormalities in the water heat exchanger 23 based on the measured values ​​received from the sensors in the refrigerant circuit 2 and the water circuit 3. In addition, if the control device 4 detects signs of refrigerant R leakage in the water heat exchanger 23, it executes a process to suppress the ingress of water W into the refrigerant circuit 2. Details of this process will be described later.

[0027] (Functional configuration of the control unit) Figure 4 is a diagram showing the functional configuration of the control device according to the first embodiment of this disclosure. As shown in Figure 4, the control device 4 includes a processor 40, main memory 41, storage 42, interface 43, and display unit 44.

[0028] The processor 40 performs the functions of a detection unit 401, a control unit 402, and an alarm unit 403 by operating according to a predetermined program.

[0029] The detection unit 401 detects abnormalities in the water heat exchanger 23 based on the measured values ​​from sensors 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 below a predetermined lower limit of saturation temperature. Furthermore, the detection unit 401 also detects whether there are any signs of refrigerant R leakage from the water heat exchanger 23 during cooling operation, heating operation, and shutdown.

[0030] When the control unit 402 detects signs of refrigerant R leakage from the water heat exchanger 23, it performs various processes to suppress the ingress of water W into the refrigerant circuit 2.

[0031] The alarm unit 403 issues an abnormality alarm via the display unit 44 when an abnormality is detected in the water heat exchanger 23. The alarm unit 403 may also issue an abnormality alarm to an external monitoring terminal (computer, smartphone, tablet, etc.) via the interface 43.

[0032] The main memory 41 is where instructions and data are loaded for the processor 40 to operate based on the program.

[0033] The storage 42 is a so-called auxiliary storage device, which may be, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive).

[0034] Interface 43 is an interface (communication interface) for communicating with each device and sensor in the refrigerant circuit 2 and the water circuit 3.

[0035] The display unit 44 is a display that shows information such as whether or not there is a malfunction in the chilling unit 1.

[0036] (Processing flow during cooling operation) Figure 5 is a flowchart showing an example of the processing during cooling operation of the control device according to the first embodiment of this disclosure. The following describes the process for monitoring abnormalities in the water heat exchanger 23 during cooling operation, and the flow of processing in the event of an abnormality, with reference to Figure 5.

[0037] The control unit 402 controls the operating state of each component 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 Figure 1, the control unit 402 switches the four-way valve 22 so that the refrigerant R discharged by the compressor 21 flows to the air heat exchanger 26, and opens the first expansion valve 241, and closes the second expansion valve 242 and the third expansion valve 243. When the compressor 21 is operated in this manner, the four-way valve 22 switches, and the circuit 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 if a water valve 32 is installed, opens it. As a result, the water W flowing through the water circuit 3 is cooled by the refrigerant R as it passes through the water heat exchanger 23.

[0038] Furthermore, during cooling operation, the detection unit 401 constantly monitors the measured value of the low-pressure side sensor 202 of the refrigerant circuit 2 (low-pressure side pressure LP of refrigerant R) to detect whether or not there is a pressure abnormality in the refrigerant. In this embodiment, each time the detection unit 401 receives a measured value from the low-pressure side sensor 202, it monitors whether the saturation temperature on the low-pressure side (hereinafter also referred to as "LP saturation temperature") has fallen below the first saturation temperature lower limit (for example, -A°C) (step S101). For example, the storage 42 has a pre-recorded correspondence table of saturation pressure and saturation temperature for each type of refrigerant R, and the detection unit 401 refers to the correspondence table to determine the LP saturation temperature. The first saturation temperature lower limit is also pre-set according to the type of refrigerant R, etc.

[0039] If the LP saturation temperature is above the first saturation temperature lower limit (step S101: NO), the detection unit 401 determines that the refrigerant pressure condition is normal. In this case, the control device 4 continues the cooling operation of the chilling unit 1.

[0040] On the other hand, if the LP saturation temperature is below 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. The alarm unit 403 also 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, etc., along with the abnormality alarm on the display unit 44. The alarm unit 403 may also issue an abnormality alarm to an external monitoring terminal, etc., via the interface 43. When the chilling unit 1 administrator issues a low pressure abnormality alarm for the refrigerant, they arrange for repairs to the chilling unit 1.

[0041] Next, the detection unit 401 checks for signs of refrigerant R leakage into the water circuit 3 in the water heat exchanger 23. Specifically, first, the detection unit 401 determines the degree of subcooling 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. In other embodiments, the first temperature sensor 203 may be a sensor capable of measuring the degree of subcooling, and the detection unit 401 may obtain the degree of subcooling at the outlet of the air heat exchanger 26 from the first temperature sensor 203. The detection unit 401 then determines whether the degree of subcooling at the outlet of the air heat exchanger 26 has fallen significantly below a predetermined subcooling standard value and whether subcooling cannot be ensured (step S103). The subcooling standard value is set in advance according to the type of refrigerant R, etc.

[0042] If the degree of supercooling at the outlet of the air heat exchanger 26 has not fallen below the supercooling standard value (step S103: NO), the detection unit 401 determines that there is no sign of refrigerant R leakage (step S105). In this case, the control unit 402 finishes the process with the operation of the chilling unit 1 stopped.

[0043] On the other hand, if the degree of supercooling at the outlet of the air heat exchanger 26 falls below the supercooling standard value (step S103: YES), the detection unit 401 further checks whether the water temperature at the outlet of the water heat exchanger 23 of the water circuit 3 immediately before the low-pressure abnormality occurred is below the lower limit of the water temperature control range (for example, 3°C) (step S104). The lower limit of the water temperature control range refers to the set temperature within the temperature range that can be set in the chilling unit 1. For example, if the settable temperature range is "4~30°C", then if the set temperature is "4°C", the lower limit is "4°C", and if the set temperature is "7°C", the lower limit is "7°C".

[0044] If there is no refrigerant leak during a low-temperature anomaly (i.e., there is sufficient refrigerant R in the refrigerant circuit 2), the water temperature will decrease as the pressure LP on the low-pressure side decreases (resulting in supercooling). Therefore, if the water temperature at the outlet of the water heat exchanger 23 measured by the second temperature sensor 303 is below the lower limit of the water temperature control range (step S104: NO), the detection unit 401 determines that there is no sign of refrigerant R leakage (step S105). In other words, it determines that the low-pressure anomaly of the refrigerant is due to a cause other than refrigerant leakage from the water heat exchanger 23, for example, a blockage in the refrigerant circuit 2. In this case, the control unit 402 finishes processing with the operation of the chilling unit 1 stopped.

[0045] On the other hand, if there is a refrigerant leak during a low-pressure abnormality, the refrigerant R will be insufficient, making it difficult to cool sufficiently until the lower limit (set temperature) is reached. Therefore, if the water temperature at the outlet of the water heat exchanger 23 is above the lower limit of the water temperature control range (step S104: YES), the detection unit 401 determines that a leak has already occurred in the water heat exchanger 23, and that refrigerant and water are mixed, making it impossible to control the water temperature. In this case, the alarm unit 403 issues an abnormal alarm indicating a refrigerant leak from the water heat exchanger 23 (step S106). When an abnormal alarm indicating a refrigerant leak from the water heat exchanger 23 is issued, the administrator of the chilling unit 1 arranges for repairs to the chilling unit 1.

[0046] Normally, the refrigerant circuit 2 is at a higher pressure than the water circuit 3. However, if the refrigerant R leaks and the pressures of the refrigerant circuit 2 and water circuit 3 become equal, water W from the water circuit 3 may enter the refrigerant circuit 2. Also, there may be a delay between arranging for repairs and the actual repair of the chilling unit 1. Therefore, if the refrigerant R leak is left unattended until the chilling unit 1 is repaired, water W may enter the refrigerant circuit 2, potentially causing damage to the chilling unit 1, such as a malfunction of the compressor 21.

[0047] To reduce the possibility of further damage to the chilling unit 1, the control unit 402 according to this embodiment performs an automatic process to suppress the ingress of water W into the refrigerant circuit 2 when a refrigerant leak is detected. The specific details of this process will be explained with reference to Figures 5 and 6.

[0048] Figure 6 shows an example of the control state when a refrigerant leak is detected in a chilling unit according to the first embodiment of this disclosure. First, let's explain the processing in the water circuit 3. If the water heat exchanger 23 is damaged, there is a possibility that water W will leak into the refrigerant circuit 2 if there is water flowing in the water circuit 3. For this reason, the control unit 402 performs a third process (step S107) which involves stopping the water pump 31 of the water circuit 3 and closing the water valve 32, as shown in Figure 6. This suppresses the ingress of water W into the refrigerant circuit 2. Furthermore, in a system in which multiple chilling units 1 are connected by a single water circuit 3, if refrigerant R leaks into the water circuit 3 of one chilling unit 1, it is possible to suppress the circulation of water W mixed with refrigerant R to other chilling units.

[0049] Next, the processing in the refrigerant circuit 2 will be explained. The control unit 402 performs a first process (steps S108 to S109) to increase the pressure in the refrigerant circuit 2 so that it does not become pressure-equal with the water circuit 3. Specifically, as shown in Figure 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 restricts 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, thereby increasing 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.

[0050] Furthermore, the control unit 402 performs 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.

[0051] 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 (step S110). The pressure upper limit is, for example, the 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, etc.

[0052] If the high-pressure side pressure HP is below the upper pressure limit (step S110: NO), the control unit 402 continues to operate the compressor 21.

[0053] On the other hand, if the high-pressure side pressure HP exceeds the upper pressure limit (step S110: YES), the control unit 402 stops the compressor 21 (step S111). This allows the control unit 402 to prevent the pressure in the section before and after the water heat exchanger 23 of the refrigerant circuit 2 from becoming unnecessarily high compared to the pressure in the water circuit 3.

[0054] Furthermore, after stopping the compressor 21, the control unit 402 checks whether the high-pressure side pressure HP has fallen below the lower pressure limit (step S112). The upper pressure limit is, for example, the value obtained by adding a predetermined margin α2 to the inlet 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, etc. Note that the values ​​of margins α1 and α2 may be the same or different.

[0055] If the high-pressure side pressure HP is equal to or greater than the lower pressure limit (step S112: NO), the control unit 402 keeps the compressor 21 stopped.

[0056] On the other hand, if the high-pressure side pressure HP falls below the lower pressure limit (step S112: YES), the control unit 402 starts the compressor 21 (returns to step S109). This allows the control unit 402 to equalize the pressure in the section of the refrigerant circuit 2 before and after the water heat exchanger 23 with that of the water circuit 3, thereby preventing water W from entering the refrigerant circuit 2.

[0057] Thus, if the control unit 402 detects signs of refrigerant R leakage during cooling operation, it performs the first to third processes as shown in Figure 5 to suppress water W from the water circuit 3 from entering the refrigerant circuit 2, thereby preventing further damage to the chilling unit 1.

[0058] (Processing flow during heating operation) Figure 7 is a flowchart showing an example of the process during heating operation of the control device according to the first embodiment of this disclosure. The following describes the process for monitoring abnormalities in the water heat exchanger 23 during heating operation, and the process for handling abnormalities, with reference to Figure 7.

[0059] The control unit 402 controls the operating state of each component 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 Figure 2, the control unit 402 switches the four-way valve 22 so that the refrigerant R discharged by the compressor 21 flows to the water heat exchanger 23, and closes the first expansion valve 241, and opens the second expansion valve 242 and the third expansion valve 243. Once the control unit 402 has switched the refrigerant circuit 2 to a flow path for heating operation, it operates the compressor 21. For 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 one is installed. As a result, the water W flowing through the water circuit 3 is heated by the refrigerant R as it passes through the water heat exchanger 23.

[0060] Furthermore, the detection unit 401 constantly monitors the pressure LP on the low-pressure side of the refrigerant R during heating operation to detect whether there is any abnormality in the water heat exchanger 23. Specifically, the detection unit 401 monitors whether the ambient temperature is 0°C or higher and whether the LP saturation temperature has fallen below the second saturation temperature lower limit (for example, -B°C) (step S201). The second saturation temperature lower limit is preset according to the type of refrigerant R, etc.

[0061] If the ambient temperature is below 0°C, or if the LP saturation temperature is above the second lower limit of the saturation temperature (step S201: NO), the detection unit 401 determines that the refrigerant circuit 2 is functioning normally (no leakage). In this case, the control device 4 continues the heating operation of the chilling unit 1.

[0062] On the other hand, if the outside temperature is 0°C or higher and the LP saturation temperature is below the second saturation temperature (step S201: YES), the detection unit 401 detects that a leak has occurred from the refrigerant circuit 2 and there may be signs of refrigerant R leakage in the water heat exchanger 23. In this case, the control unit 402 stops the heating operation of the chilling unit 1. The alarm unit 403 also issues an abnormal alarm indicating signs of refrigerant leakage in the water heat exchanger 23 (step S202).

[0063] When the control unit 402 detects signs of refrigerant leakage, it performs a process to suppress the ingress of water W into the refrigerant circuit 2, similar to the process during cooling operation.

[0064] With respect to the water circuit 3, the control unit 402 performs a third process (step S203) which involves stopping the water pump 31 of the water circuit 3 and closing the water valve 32. This process is the same as step S107 in Figure 5.

[0065] Regarding the refrigerant circuit 2, first, the control unit 402 performs a first process (steps S204 to S205) to increase the pressure in the refrigerant circuit 2 so that it does not become pressure-equal with the water circuit 3. If the heating operation is stopped in step S202, the flow path may switch to the stopped flow path shown in Figure 3. For this reason, as shown in Figure 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 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. These processes are the same as steps S108 to S109 in Figure 5.

[0066] Furthermore, the control unit 402 performs 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 Figure 5.

[0067] If the control unit 402 detects signs of refrigerant R leakage during heating operation, it performs the first to third processes as shown in Figure 7, which reduces the pressure in the refrigerant circuit 2 and prevents water W from the water circuit 3 from entering the refrigerant circuit 2.

[0068] (Processing flow when the system is shut down) Figure 8 is a flowchart showing an example of the process when the control device according to the first embodiment of this disclosure is shut down. The following describes the process for monitoring abnormalities in the water heat exchanger 23 during shutdown, and the process for handling abnormalities, with reference to Figure 8.

[0069] The control unit 402, in accordance with the operation of the administrator of the chilling unit 1, puts the chilling unit 1 into an operational stop state (step S300). At this time, as shown in Figure 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. The control unit 402 also stops the water pump 31 and closes the water valve 32. In other embodiments, the control unit 402 may keep the water pump 31 running and the water valve 32 open even when the unit is stopped for protective control purposes.

[0070] Furthermore, the detection unit 401 constantly monitors the low-pressure side pressure LP or high-pressure side pressure HP of the refrigerant R while the system is stopped, and detects whether there is any abnormality in the water heat exchanger 23. Specifically, the detection unit 401 monitors whether the ambient temperature is 0°C or higher, and whether the saturation temperature of LP or the high-pressure side saturation temperature (hereinafter also referred to as "HP saturation temperature") has fallen below the third saturation temperature lower limit (for example, -°C) (step S301). The third saturation temperature lower limit is set in advance according to the type of refrigerant R, etc.

[0071] If the ambient temperature is below 0°C, or if the LP saturation temperature or HP saturation temperature is above the third saturation temperature lower limit (step S301: NO), the detection unit 401 determines that there is no problem with the refrigerant circuit 2 and that the water heat exchanger 23 is functioning correctly. In this case, the control device 4 keeps the chilling unit 1 in a stopped state.

[0072] On the other hand, if the outside temperature is 0°C or higher, and the LP saturation temperature or HP saturation temperature is below the third saturation temperature (step S301: YES), the detection unit 401 detects that a leak has occurred from the refrigerant circuit 2 and that there may be signs of refrigerant R leakage in the water heat exchanger 23. In this case, the alarm unit 403 issues an abnormal alarm indicating signs of refrigerant leakage from the refrigerant circuit 2 (step S302).

[0073] When the control unit 402 detects signs of refrigerant leakage, it performs a process to suppress the ingress of water W into the refrigerant circuit 2, similar to the process during cooling operation.

[0074] If the water pump 31 is to be operated even when the system is stopped, the control unit 402 performs a third process (step S303) to stop the water pump 31 of the water circuit 3 and close the water valve 32. This process is the same as step S107 in Figure 5. Note that if the water pump 31 is to be stopped while the system is stopped, step S303 may be omitted.

[0075] Regarding the refrigerant circuit 2, first, the control unit 402 performs a first process (steps S304 to S305) to increase the pressure of the refrigerant circuit 2 so that it does not become pressure-equal with the water circuit 3. These processes are the same as steps S108 to S109 in Figure 5.

[0076] Furthermore, the control unit 402 performs 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 Figure 5.

[0077] If the control unit 402 detects signs of refrigerant R leakage while the system is stopped, it performs the first to third processes as shown in Figure 8, which reduces the pressure in the refrigerant circuit 2 and prevents water W from the water circuit 3 from entering the refrigerant circuit 2.

[0078] In this embodiment, the detection unit 401 detects in step S301 of Figure 8 that there are signs of refrigerant R leakage when the ambient temperature is 0°C or higher and the LP saturation temperature or HP saturation temperature is below the third saturation temperature (condition 1 is met), and performs maintenance control in steps S303 to S308 assuming leakage from the water heat exchanger 23, but is not limited to this. In other embodiments, the detection unit 401 may detect in step S301 that there are signs of refrigerant R leakage from the water heat exchanger 23 when, instead of condition 1, or in addition to condition 1, another condition (condition 2) is met. Condition 2 is met, for example, when the ambient temperature is 0°C or higher, the difference between the LP saturation temperature (or HP saturation temperature) and the ambient temperature is a predetermined temperature difference (e.g., 10 degrees) or more, and the change in the LP saturation temperature (or HP saturation temperature) does not follow the temperature change of the ambient temperature. The detection unit 401 can detect refrigerant leakage of refrigerant R by confirming whether condition 2 is met.

[0079] Figures 5, 7, and 8 show an example in which the control unit 402 executes the first process (steps S108-S109, S204-S205, S304-S305) after the third process (steps S107, S203, S303), but 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.

[0080] (Effect, Action) As described above, in the chilling unit 1 according to this embodiment, the control device 4 has a detection unit 401 that detects an abnormality in the water heat exchanger 23 when the LP saturation temperature or HP saturation temperature of the refrigerant circuit 2 is below a predetermined lower limit of saturation temperature.

[0081] In this way, the chilling unit 1 can quickly detect any abnormalities in the water heat exchanger 23.

[0082] Furthermore, the detection unit 401 of the control device 4 detects an abnormality indicating refrigerant leakage in the water heat exchanger 23 when, during cooling operation, the LP saturation temperature of the refrigerant circuit 2 is below the first saturation temperature lower limit, the degree of subcooling at the outlet of the air heat exchanger 26 falls below the subcooling degree reference value, and the water temperature at the outlet of the water heat exchanger 23 of the water circuit 3 is above the lower limit of the water temperature control range.

[0083] In this way, the chilling unit 1 can quickly detect refrigerant leakage during cooling operation.

[0084] Furthermore, the detection unit 401 of the control device 4 detects an abnormality indicating refrigerant leakage in the water heat exchanger 23 when the LP saturation temperature of the refrigerant circuit 2 is below the second saturation temperature lower limit during heating operation.

[0085] In this way, the chilling unit 1 can quickly detect signs of refrigerant leakage during heating operation.

[0086] Furthermore, the detection unit 401 of the control device 4 detects an abnormality indicating refrigerant leakage in the water heat exchanger 23 when the LP saturation temperature or HP saturation temperature of the refrigerant circuit 2 is below the third saturation temperature lower limit while the device is stopped.

[0087] In this way, the chilling unit 1 can quickly detect signs of refrigerant leakage while the system is shut down.

[0088] Furthermore, the control device 4 also includes a control unit 402 that, upon detecting signs of refrigerant leakage, closes the first expansion valve 241 and the second expansion valve 242, switches the four-way valve 22 to create a flow path for heating operation, and starts the compressor 21, thereby executing a first process.

[0089] In this way, the chilling unit 1 can maintain a state where the refrigerant circuit 2 is at a higher pressure than the water circuit 3 until the water heat exchanger 23 is repaired or replaced, thereby suppressing the ingress of water W into the refrigerant circuit 2. This reduces the possibility that water that enters the refrigerant circuit 2 may damage the equipment connected to the refrigerant circuit 2.

[0090] Furthermore, after executing the first process, the control unit 402 of the control device 4 further executes a second process in which it stops the compressor 21 when the high-pressure side pressure HP of the refrigerant circuit 2 exceeds the upper pressure limit, and starts the compressor 21 when the high-pressure side pressure HP of the refrigerant circuit 2 falls below the lower pressure limit.

[0091] In this way, 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. This prevents water W from entering the refrigerant circuit 2 from the water circuit 3.

[0092] Furthermore, the control unit 402 of the control device 4 sets the lower pressure limit to a value obtained by adding a predetermined margin α2 to the inlet pressure WP1 of the water circuit 3.

[0093] In this way, the chilling unit 1 can maintain a pressure higher than the pressure in the water circuit 3 in the section of the refrigerant circuit 2 before and after the water heat exchanger 23. This makes it possible to more reliably suppress the intrusion of water W from the water circuit 3 into the refrigerant circuit 2.

[0094] Furthermore, if the control unit 402 of the control device 4 detects signs of refrigerant leakage, it further performs a third process which involves stopping the water pump 31 and closing the water valve 32.

[0095] By doing so, the flow of water W in the water circuit 3 can be reliably stopped, thereby suppressing the intrusion of water W into the refrigerant circuit 2. Furthermore, in a system in which multiple chilling units 1 are connected by a single water circuit 3, if refrigerant R leaks into the water circuit 3 of one chilling unit 1, it is possible to prevent the water W mixed with refrigerant R from circulating to other chilling units.

[0096] As described above, several embodiments relating to this disclosure have been explained, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0097] <Note> The chilling unit, control method, and program described in the above-described embodiment can be understood, for example, as follows.

[0098] (1) According to a first aspect of the present disclosure, the chilling unit (1) includes a refrigerant circuit (2) having a compressor (21) for compressing a refrigerant, an air heat exchanger (26) for exchanging heat between the refrigerant and outside air, a water heat exchanger (23) for exchanging heat between the refrigerant and water, an expansion valve (24) provided between the air heat exchanger (26) and the water heat exchanger (23), and a four-way valve (22) for switching the flow path of the refrigerant between a flow path for cooling operation and a flow path for heating operation, and inserted into the water heat exchanger (23) The system includes a water circuit (3) having a water pipe (30), a water pump (31) that supplies water to the water pipe (30), and a water valve (32) provided downstream of the water heat exchanger (23) in the water pipe (30), and a control device (4) that controls the refrigerant circuit (2) and the water circuit (3). The control device (4) has a detection unit (401) that detects an abnormality in the water heat exchanger (23) when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit (2) is below a predetermined lower limit of saturation temperature.

[0099] In this way, the chilling unit can quickly detect abnormalities in the water heat exchanger.

[0100] (2) According to a 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 an abnormality indicating refrigerant leakage in the water heat exchanger (23) when, during cooling operation, the saturation temperature on the low-pressure side of the refrigerant circuit (2) is below the first saturation temperature lower limit, the degree of subcooling at the outlet of the air heat exchanger (26) falls below the subcooling degree reference value, and the water temperature at the outlet of the water heat exchanger (23) of the water circuit (3) is above the lower limit of the water temperature control range.

[0101] In this way, the chilling unit can quickly detect refrigerant leaks during cooling operation.

[0102] (3) According to a third aspect of the present disclosure, in a chilling unit (1) according to the first or second aspect, the detection unit (401) of the control device (4) detects an abnormality indicating a refrigerant leak in the water heat exchanger (23) when the saturation temperature on the low-pressure side of the refrigerant circuit (2) is below the second saturation temperature lower limit during heating operation.

[0103] In this way, the chilling unit 1 can quickly detect signs of refrigerant leakage during heating operation.

[0104] (4) According to a fourth aspect of the present disclosure, in a chilling unit (1) according to any one of the first to third aspects, the detection unit (401) of the control device (4) detects an abnormality indicating a refrigerant leak in the water heat exchanger (23) when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit (2) is below the third saturation temperature lower limit during shutdown.

[0105] In this way, the chilling unit can quickly detect signs of refrigerant leakage while the system is shut down.

[0106] (5) According to a fifth aspect of the present disclosure, in a chilling unit (1) according to any one of the second to fourth aspects, the control device (4) further has a control unit (402) that, when it detects signs of refrigerant leakage, closes the expansion valve (24), switches the four-way valve (22) to become a flow path for heating operation, and starts the compressor (21).

[0107] In this way, the chilling unit can maintain a higher pressure in the refrigerant circuit than in the water circuit until the water heat exchanger is repaired or replaced, thereby preventing water from entering the refrigerant circuit. This reduces the possibility of damage to the equipment connected to the refrigerant circuit due to water entering the circuit.

[0108] (6) According to a sixth aspect of the present disclosure, in a chilling unit (1) according to a fifth aspect, the control unit (402) of the control device (4) further performs a second process in which, after performing a first process, the compressor (21) is stopped when the pressure on the high-pressure side of the refrigerant circuit (2) becomes equal to or greater than the upper pressure limit, and the compressor (21) is started when the pressure on the high-pressure side of the refrigerant circuit (2) becomes less than the lower pressure limit.

[0109] In this way, the chilling unit can maintain the pressure in the section of the refrigerant circuit before and after the water heat exchanger within a certain range. This prevents water from entering the refrigerant circuit from the water circuit.

[0110] (7) According to the seventh aspect of the present disclosure, in the chilling unit (1) according to the sixth aspect, the control unit (402) of the control device (4) sets the pressure lower limit to a value obtained by adding a predetermined margin to the measured pressure on the inlet side of the water circuit (3).

[0111] In this way, the chilling unit can maintain a pressure higher than the water pressure in the section of the refrigerant circuit before and after the water heat exchanger. This more effectively prevents water from entering the refrigerant circuit from the water circuit.

[0112] (8) According to the eighth aspect of the present disclosure, in a chilling unit (1) according to any one of the fifth to seventh aspects, the control unit (402) of the control device (4) further performs a third process of stopping the water pump (31) and closing the water valve (32) when it detects signs of refrigerant leakage.

[0113] By doing so, the flow of water in the water circuit can be reliably stopped, thereby preventing water from entering the refrigerant circuit. Furthermore, in a system where multiple chilling units are connected by a single water circuit, if refrigerant leaks into the water circuit of one chilling unit, it is possible to prevent the water contaminated with refrigerant from circulating to other chilling units.

[0114] (9) According to a ninth aspect of the present disclosure, a control method for a chilling unit comprising: a refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for performing heat exchange between the refrigerant and outside air, a water heat exchanger for performing heat exchange between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant to a flow path for cooling operation or a flow path for heating operation; a water circuit having a water pipe inserted into the water heat exchanger, a water pump for supplying water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe; and a control device for controlling the refrigerant circuit and the water circuit, wherein the control device detects an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature.

[0115] (10) According to a tenth aspect of the present disclosure, the program causes a control device for a chilling unit, which includes a refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant to a flow path for cooling operation or a flow path for heating operation, and a water circuit having a water pipe inserted into the water heat exchanger, a water pump for supplying water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe, to perform the step of detecting an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature. [Explanation of Symbols]

[0116] 1 Chilling Unit 2 Refrigerant Circuit 20 Refrigerant piping 201 High-voltage 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 receivers 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 processors 401 Detection Unit 402 Control Unit 403 Alarm section 41 Main memory 42 storage 43 Interfaces 44 Display section

Claims

1. A refrigerant circuit having a compressor for compressing a refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant between a flow path for cooling operation and a flow path for heating operation, A water circuit comprising a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe, A control device for controlling the refrigerant circuit and the water circuit, Equipped with, The control device has a detection unit that detects an abnormality in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature. The detection unit of the control device detects an abnormality indicating refrigerant leakage in the water heat exchanger when, during cooling operation, the saturation temperature on the low-pressure side of the refrigerant circuit is below the first lower limit of saturation temperature, the degree of subcooling at the outlet of the air heat exchanger falls below the subcooling standard value, and the water temperature at the outlet of the water heat exchanger of the water circuit is above the lower limit of the water temperature control range. Chilling unit.

2. The detection unit of the control device detects an abnormality indicating a refrigerant leak in the water heat exchanger when the saturation temperature on the low-pressure side of the refrigerant circuit is below the second lower limit of the saturation temperature during heating operation. The chilling unit according to claim 1.

3. The detection unit of the control device detects an abnormality indicating refrigerant leakage in the water heat exchanger when the saturation temperature on the low-pressure side or high-pressure side of the refrigerant circuit is below the third lower limit of saturation temperature during shutdown. Chilling unit according to claim 1 or 2.

4. The control device further includes a control unit that, upon detecting signs of refrigerant leakage, closes the expansion valve, switches the four-way valve to create a flow path for the heating operation, and starts the compressor, thereby executing a first process. A chilling unit according to any one of claims 1 to 3.

5. The control unit of the control device, after executing the first process, further executes a second process in which it stops the compressor when the pressure on the high-pressure side of the refrigerant circuit exceeds the upper pressure limit, and starts the compressor when the pressure on the high-pressure side of the refrigerant circuit falls below the lower pressure limit. The chilling unit according to claim 4.

6. The control unit of the control device sets the pressure lower limit to a value obtained by adding a predetermined margin to the measured pressure value on the inlet side of the water circuit. The chilling unit according to claim 5.

7. The control unit of the control device, upon detecting signs of refrigerant leakage, further performs a third process of stopping the water pump and closing the water valve. A chilling unit according to any one of claims 4 to 6.

8. A refrigerant circuit having a compressor for compressing the refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant between a flow path for cooling operation and a flow path for heating operation, A water circuit comprising a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe, A control device for controlling the refrigerant circuit and the water circuit, A method for controlling a chilling unit, comprising: The control device detects an abnormality in the water heat exchanger when the saturation temperature on the low-pressure or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature. It has, The step of detecting an abnormality in the water heat exchanger involves detecting an abnormality indicating refrigerant leakage in the water heat exchanger when, during cooling operation, the saturation temperature on the low-pressure side of the refrigerant circuit is below the first lower limit of saturation temperature, the degree of subcooling at the outlet of the air heat exchanger falls below the subcooling standard value, and the water temperature at the outlet of the water heat exchanger in the water circuit is above the lower limit of the water temperature control range. Control method.

9. A refrigerant circuit having a compressor for compressing the refrigerant, an air heat exchanger for exchanging heat between the refrigerant and outside air, a water heat exchanger for exchanging heat between the refrigerant and water, an expansion valve provided between the air heat exchanger and the water heat exchanger, and a four-way valve for switching the flow path of the refrigerant between a flow path for cooling operation and a flow path for heating operation, A water circuit comprising a water pipe inserted into the water heat exchanger, a water pump for supplying the water to the water pipe, and a water valve provided downstream of the water heat exchanger in the water pipe, A control device for a chilling unit equipped with: Step 1: Detect an abnormality in the water heat exchanger when the saturation temperature on the low-pressure or high-pressure side of the refrigerant circuit is below a predetermined lower limit of saturation temperature. A program that executes, The step of detecting an abnormality in the water heat exchanger involves detecting an abnormality indicating refrigerant leakage in the water heat exchanger when, during cooling operation, the saturation temperature on the low-pressure side of the refrigerant circuit is below the first lower limit of saturation temperature, the degree of subcooling at the outlet of the air heat exchanger falls below the subcooling standard value, and the water temperature at the outlet of the water heat exchanger in the water circuit is above the lower limit of the water temperature control range. program.

Images