Chilling unit

Abstract

The present invention provides a chilling unit comprising: a heat medium piping section which forms part of a heat medium circuit and in which a heat medium is distributed; a refrigerant circuit having a compressor that compresses a refrigerant, the refrigerant being circulated by the compressor; a heat medium heat exchanger having a heat medium channel through which the heat medium is distributed and a refrigerant channel through which the refrigerant is distributed, the heat medium heat exchanger being provided in the heat medium piping section, forming part of the heat medium circuit and the refrigerant circuit, and performing heat exchange between the heat medium and the refrigerant; a pump which is installed upstream of the heat medium heat exchanger in the heat medium piping section and which delivers the heat medium to the heat medium heat exchanger; a pre-pump pressure sensor that detects the heat medium pressure on the suction side of the pump; an inlet pressure sensor that detects the heat medium pressure on the discharge side of the pump and the heat medium inlet side of the heat medium heat exchanger; and an outlet pressure sensor that detects the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger.

Description

Chilling Unit

[0001] The present disclosure relates to a chilling unit with a water pressure sensor.

[0002] Chilling units are used as heat sources in water circulation air conditioning systems that circulate water within buildings, such as buildings or large commercial facilities. Chilling units have a refrigerant circuit through which a refrigerant circulates and a portion of a water circuit through which water, a heat medium, circulates within the building. Heat is transported via the water circuit to load-side equipment (e.g., a fan coil unit or an air handling unit) for heating and cooling. The refrigerant circuit includes a compressor that compresses the refrigerant, and the water circuit includes a pump that pumps water. In such chilling units, it is effective to use inverter-compatible compressors and pumps. To control the inverters for these compressors and pumps, water temperature is measured to optimize control for the load. Chilling units can adjust the water flow rate according to the load, and when the load is low, the water flow rate is reduced to reduce the power required to transport water, thereby achieving power savings. Some chilling units equipped with pumps that can change the water flow rate include water pressure sensors at the water inlet and outlet of the water heat exchanger, which is a heat medium heat exchanger that exchanges heat between the refrigerant and water (see, for example, Patent Document 1).

[0003] The chilling unit of Patent Document 1 is configured to estimate the flow rate of water flowing through the water heat exchanger from the difference in water pressure at the water inlet and outlet of the water heat exchanger, and to control the pump so that the estimated flow rate is above the lower limit flow rate during operation determined by the pump characteristics, thereby preventing internal freezing of the water heat exchanger.

[0004] Patent No. 6570746

[0005] However, in a configuration such as the chilling unit of Patent Document 1, in which water pressure sensors are installed in only two locations, between the pump and the water inlet of the water heat exchanger, and on the water outlet side of the water heat exchanger, it was difficult to distinguish between abnormalities around the water heat exchanger and abnormalities occurring elsewhere around the pump.

[0006] The present disclosure is intended to solve the above-mentioned problem, and aims to provide a chilling unit that can distinguish between abnormalities around the water heat exchanger (heat medium heat exchanger) and abnormalities around the pump.

[0007] The chilling unit according to the present disclosure comprises a heat medium piping section through which a heat medium flows, a refrigerant circuit having a compressor for compressing a refrigerant and in which the refrigerant is circulated by the compressor, a heat medium flow path through which the heat medium flows, and a refrigerant flow path through which the refrigerant flows, the chilling unit being provided in the heat medium piping section and constituting both the heat medium circuit and a part of the refrigerant circuit, the chilling unit comprising: a heat medium heat exchanger for exchanging heat between the heat medium and the refrigerant, a pump provided in the heat medium piping section upstream of the heat medium heat exchanger for delivering the heat medium to the heat medium heat exchanger, a pre-pump pressure sensor for detecting the heat medium pressure on the suction side of the pump, an inlet pressure sensor on the discharge side of the pump for detecting the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger, and an outlet pressure sensor for detecting the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger.

[0008] In the chilling unit according to the present disclosure, water pressure sensors are provided on the suction side of the pump and on the heat medium inlet and outlet sides of the heat medium heat exchanger, making it possible to distinguish between abnormalities around the heat medium heat exchanger and abnormalities around the pump.

[0009] Fig. 1 is a circuit diagram showing a schematic configuration of a water circulation air conditioning system including a chilling unit according to an embodiment of the present disclosure as a heat source machine. Fig. 2 is a block diagram showing the functions of the control device of Fig. 1. Fig. 3 is a diagram showing the relationship between head loss and flow rate of the water heat exchanger of Fig. 1. Fig. 4 is a diagram showing the relationship between head and flow rate of the pump of Fig. 1. Fig. 5 is a flowchart showing control during a test run of the chilling unit of Fig. 1. Fig. 6 is a flowchart showing abnormality determination control for the chilling unit of Fig. 1. Fig. 7 is an explanatory diagram showing criteria for each abnormality determination by the control device of Fig. 1.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the specification. Furthermore, the forms of the components shown in the entire specification are merely examples and are not intended to be limiting.

[0011] 1 is a circuit diagram showing the schematic configuration of a water circulation air conditioning system equipped with a chilling unit according to an embodiment of the present disclosure as a heat source. In this embodiment, a water circulation air conditioning system 100 will be described as an example of a heat medium circulation system. The water circulation air conditioning system 100 includes a chilling unit 1 and a water circuit 2, a portion of which is disposed in the chilling unit 1. The water circulating through the water circuit 2 corresponds to the heat medium of the present disclosure, and the water circuit 2 corresponds to the heat medium circuit of the present disclosure. Brine may also be used as the heat medium. In FIG. 1, the direction of water flow is indicated by solid arrows.

[0012] The chilling unit 1 includes a refrigerant circuit 10, a portion of a water circuit 2, and a control device 7. The portion of the water circuit 2 included in the chilling unit 1 is composed of a water piping section 2a and a pump 3 and other components provided in the water piping section 2a. The water piping section 2a is the heat medium piping section of the present disclosure. The refrigerant circuit 10 of the chilling unit 1 is configured so that a refrigerant circulates by connecting a compressor 11, a heat source-side heat exchanger 12, a throttling device 13, and a water heat exchanger 14 through piping connections.

[0013] The compressor 11 compresses a heat source-side refrigerant, such as chlorofluorocarbon. The compressor 11 is inverter-controlled by the control device 7. The heat source-side heat exchanger 12 exchanges heat between the refrigerant and air, such as outside air. A blower fan 15 is disposed adjacent to the heat source-side heat exchanger 12, blowing air into the heat source-side heat exchanger 12. The blower fan 15 is inverter-controlled by the control device 7. The throttling device 13 adjusts the pressure of the refrigerant. The opening and closing of the throttling device 13 is controlled by the control device 7. The throttling device 13 may be, for example, a valve with an adjustable opening, such as a linear expansion valve (LEV). However, the throttling device 13 may also be a capillary tube with an inadjustable opening. The water heat exchanger 14 exchanges heat with water, which is different from the refrigerant. The water heat exchanger 14 uses the heat of the refrigerant to cool the water in the water circuit 2 to a desired temperature. The water heat exchanger 14 has a refrigerant flow path through which the refrigerant flows and a water flow path through which water flows, and constitutes the refrigerant circuit 10 and also constitutes the water circuit 2. The water heat exchanger 14 is, for example, a plate-type heat exchanger, and is configured so that the refrigerant flow path and the water flow path are alternately overlapped to directly exchange heat. The water heat exchanger 14 corresponds to the heat medium heat exchanger of the present disclosure. The water flow path corresponds to the heat medium flow path of the present disclosure.

[0014] The refrigerant flowing through the refrigerant circuit 10 may be, for example, a single refrigerant such as R-22 or R-134a, a pseudo-azeotropic refrigerant mixture such as R-410A or R-404A, or a non-azeotropic refrigerant mixture such as R-407C. ３ CF=CH ２ Refrigerants with relatively low global warming potential, such as CO ２ Natural refrigerants such as propane can be used.

[0015] The water circuit 2 is configured to circulate water by connecting the chilling unit 1 and the load-side heat exchanger 4 with pipes. Specifically, the water circuit 2 is configured by connecting the pump 3, the water flow path of the water heat exchanger 14, and the load-side heat exchanger 4 with pipes. The pump 3 of the chilling unit 1 circulates water used for heat exchange in the water heat exchanger 14 through the water circuit 2. The pump 3 is inverter-controlled by the control device 7.

[0016] The load-side heat exchanger 4 is, for example, a fan coil unit or an air handling unit installed in a building, and uses water from the water circuit 2 to cool indoor air.

[0017] The control device 7 is configured with dedicated hardware or a CPU (Central Processing Unit) that executes programs stored in memory. The CPU is also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or processor.

[0018] When the control device 7 is dedicated hardware, the control device 7 may be, for example, a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Each functional unit realized by the control device 7 may be realized by a separate piece of hardware, or each functional unit may be realized by a single piece of hardware.

[0019] When the control device 7 is a CPU, each function executed by the control device 7 is realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory. The CPU realizes each function of the control device 7 by reading and executing the programs stored in memory. Here, the memory is, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM.

[0020] A part of the functions of the control device 7 may be realized by dedicated hardware, and a part may be realized by software or firmware.

[0021] In FIG. 1, the control device 7 is provided inside the chilling unit 1 in the water circulation air conditioning system 100, but this is not limitative and the control device 7 may be provided outside the chilling unit 1.

[0022] The water circulation air conditioning system 100 also includes various sensors. Specifically, the chilling unit 1 includes a pre-pump pressure sensor 81 provided on the water suction side of the pump 3 that pumps water to the water heat exchanger 14, an inlet pressure sensor 82 provided between the pump 3 and the water heat exchanger 14, i.e., on the water inlet side of the water heat exchanger 14, and an outlet pressure sensor 83 provided on the water outlet side of the water heat exchanger 14. The inlet pressure sensor 82 detects the water pressure at the water inlet of the water heat exchanger 14. The outlet pressure sensor 83 detects the water pressure at the water outlet of the water heat exchanger 14. The pre-pump pressure sensor 81 detects the water pressure at the water inlet of the pump 3 provided upstream of the water heat exchanger 14. The water inlet of the water heat exchanger 14 corresponds to the heat medium inlet of the water heat exchanger 14 in this disclosure, and the water outlet of the water heat exchanger 14 corresponds to the heat medium outlet of the water heat exchanger 14 in this disclosure. The water pressure corresponds to the heat medium pressure in this disclosure.

[0023] Hereinafter, the pressure value detected by the pre-pump pressure sensor 81 will be defined as P1, the pressure value detected by the inlet pressure sensor 82 as P2, and the pressure value detected by the outlet pressure sensor 83 as P3. The pressure values ​​P1, P2, and P3 of the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 are defined based on the atmospheric pressure being 0 [kPa], with values ​​equal to or greater than 0 being positive pressure and values ​​less than 0 being negative pressure.

[0024] The various sensors provided in the water circulation air conditioning system 100 may further include sensors other than those described above. For example, the chilling unit 1 may be provided with an inlet temperature sensor that detects the water temperature at the water inlet of the water heat exchanger 14, and an outlet temperature sensor that detects the water temperature at the water outlet of the water heat exchanger 14. The load-side heat exchanger 4 may also be provided with an indoor temperature sensor that detects the indoor temperature.

[0025] The control device 7 is connected to various sensors, such as a pre-pump pressure sensor 81, an inlet pressure sensor 82, and an outlet pressure sensor 83, via wireless or wired control signal lines, and detection values ​​of the various sensors are input to the control device 7. The control device 7 is also connected to a remote control 6 via wireless or wired control signal lines. The control device 7 is configured to change the operating condition settings in response to a user's operation of the remote control 6, and to display the changed operating condition settings on the remote control 6. The control device 7 is also connected to each actuator, such as the compressor 11, the blower fan 15, the expansion device 13, and the pump 3, via wireless or wired control signal lines, and is capable of transmitting operating instructions from the control device 7 to each actuator.

[0026] Figure 2 is a block diagram showing the functions of the control device 7 of Figure 1. As shown in Figure 2, the control device 7 has, as functional units, an input unit 71, a calculation unit 72, a control unit 73, and a storage unit 74. The input unit 71 is a functional unit to which detected values ​​of various sensors, such as a pre-pump pressure sensor 81, an inlet pressure sensor 82 on the water inlet side of the water heat exchanger 14, and an outlet pressure sensor 83 on the water outlet side of the water heat exchanger 14, are input. In addition, the input unit 71 receives input from the remote control 6 of information such as start and stop of operation and the user-side set temperature during operation.

[0027] The memory unit 74 is a functional unit that stores the setting information input to the input unit 71, various control values ​​used by the control unit 73, and judgment criteria used for various abnormality judgments by the calculation unit 72. Furthermore, during a test run immediately after the water circulation air-conditioning system 100 is constructed, the memory unit 74 stores the detected values ​​from the pre-pump pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 input to the input unit 71 in association with the operating frequency of the pump 3 at that time.

[0028] The calculation unit 72 is a functional unit that calculates control parameters for each actuator based on the information input to the input unit 71 and the information stored in the storage unit 74. The calculation unit 72 also performs various abnormality determinations based on the information input to the input unit 71 and the information stored in the storage unit 74, and outputs necessary information based on the results of these abnormality determinations to a notification unit 99, which will be described later. Details of the various abnormality determinations will be described later.

[0029] As an example of abnormality determination, during operation after the start of operation, the calculation unit 72 determines and detects abnormalities around the water heat exchanger 14 and the pump 3 based on pressure values ​​P1, P2, and P3 detected by the pre-pump pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83, and pressure values ​​(pressure values ​​P21, P22, P23, P31, P32, and P33 described below) previously stored in the storage unit 74. These pressure values ​​P21, P22, P23, P31, P32, and P33 used in abnormality determination will be described below.

[0030] The control unit 73 is a functional unit that controls each actuator of the compressor 11, the blower fan 15, the expansion device 13, the pump 3, etc., based on the control parameters calculated by the calculation unit 72. Specifically, the control unit 73 controls the frequency of the compressor 11, the rotation speed of the blower fan 15, the opening degree of the expansion device 13, the frequency of the pump 3, etc.

[0031] The chilling unit 1 also includes an alarm unit 99 that reports abnormality information when an abnormality is detected by the calculation unit 72. Here, abnormality information refers to, for example, the result of an abnormality determination indicating the cause when the flow rate calculated from the pressure difference (P2-P3) across the water heat exchanger 14 is outside the operating flow rate range, or treatment information indicating the treatment to be performed in response to the abnormality determination result. The alarm unit 99 may also be configured to report abnormality information, such as the result of an abnormality determination and treatment information, when certain conditions are met, even if the flow rate calculated from the pressure difference (P2-P3) across the water heat exchanger 14 is within the operating flow rate range. The alarm unit 99 may be configured, for example, to report abnormality information using a liquid crystal display or speaker, and may report the abnormality information in text, audio, or light. With this configuration, for example, a worker performing a periodic inspection can check the abnormality information displayed on the alarm unit 99 to identify abnormalities in the water flow around the water heat exchanger 14 and the pump 3 and the location of the abnormality.

[0032] FIG. 3 shows the head loss [kPa] and flow rate [m ３ 4 is a graph showing the relationship between the head [kPa] and flow rate [m ３5 is a flowchart showing the control during a test run of the chilling unit 1 of FIG. 1. The characteristics of the water heat exchanger 14, the characteristics of the pump 3, and the operation during a test run of the water circulation air conditioning system 100 will be described below with reference to FIGS. 3 to 5.

[0033] In the chilling unit 1 of the present disclosure, the control device 7 identifies multiple abnormalities that could cause changes in the water flow rate in the water heat exchanger 14 and the pump 3 based on the pressure values ​​P1, P2, and P3 detected by the pre-pump pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83.

[0034] In FIG. 3 , the horizontal axis represents the flow rate of water flowing through the water heat exchanger 14, and the vertical axis represents the head loss of water in the water heat exchanger 14. The head loss is the differential pressure (P2-P3) across the water heat exchanger 14 and varies depending on, for example, the number of plates constituting the water heat exchanger 14, the length and resistance of the water flow path, and other factors. In FIG. 4 , the horizontal axis represents the flow rate of water that can be delivered by the pump 3, and the vertical axis represents the head. The head is the amount of water pressure increase caused by the pump 3 and is the differential pressure (P2-P1) across the pump 3. FIG. 4 also shows pump head curves C1, C2, and C3, which represent the relationship between the water flow rate and head when the operating frequencies of the pump 3 are the lower operating frequency limit Fp1, the upper operating frequency limit Fp2, and the rated frequency Fp3 (Fp1<Fp2<Fp3). Here, the rated frequency Fp3 is, for example, the maximum frequency of the pump 3.

[0035] 3, as the flow rate of water flowing through the water heat exchanger 14 increases, the flow velocity of the water flowing through the water heat exchanger 14 increases, and the head loss of the water in the water heat exchanger 14, i.e., the differential pressure (P2-P3) before and after the water heat exchanger 14, increases. However, for example, if the width of the water flow path of the water heat exchanger 14 narrows due to scale accumulation in the water flow path or freezing of the water flow path, the relationship between the head loss, i.e., the differential pressure (P2-P3) and the water flow rate, may deviate from the head loss diagram in FIG.

[0036] Also, as shown in Figure 4, for the same operating frequency, the higher the flow rate of water pumped out by pump 3, the smaller the head. For the same flow rate, the higher the operating frequency of pump 3, the greater the head. Also, for the same head, the higher the operating frequency of pump 3, the greater the flow rate. However, if an abnormality such as air entrapment occurs inside pump 3 and the pump 3 is unable to perform to its full potential, the flow rate of water pumped out by pump 3 decreases, the pressure value P2 on the water discharge side of pump 3 decreases, and the head, i.e., the differential pressure (P2 - P1), decreases. In this way, the relationship between head, i.e., the differential pressure (P2 - P1), and flow rate may deviate from the pump head curves C1 to C3 in Figure 4.

[0037] The characteristics of the water heat exchanger 14 shown in Figure 3 (i.e., the head loss diagram) and the characteristics of the pump 3 shown in Figure 4 (i.e., the pump head diagrams such as pump head curves C1 to C3) are stored in advance as initial characteristic data in the storage unit 74, for example, at the time of shipment of the chilling unit 1. Note that the characteristics of the pump 3 shown in Figure 4 do not have to be stored in the storage unit 74 at the time of shipment. In that case, the operating range of the pump 3 for a specified flow rate range may be automatically set during trial operation using the method described below.

[0038] (During trial run of water circulation air conditioning system 100) As shown in Figure 5, during trial run immediately after construction of water circulation air conditioning system 100, the operating range of pump 3 is set, and pressure values ​​P1, P2, and P3 are measured when pump 3 is driven at multiple frequencies, and these pressure values ​​are stored in memory unit 74. Immediately after construction of water circulation air conditioning system 100, there is no scale buildup in water heat exchanger 14, the original water flow path is maintained, and the relationship between head loss and flow rate in water heat exchanger 14 is the same as the relationship stored in memory unit 74 at the time of shipment of chilling unit 1 (see Figure 3). Chilling unit 1 has a program for carrying out the following steps S1 to S5.

[0039] (Step S1) First, the chilling unit 1 automatically adjusts the operating frequency of the pump 3 to match the head loss (i.e., P2-P3) to the operational upper limit flow rate V2 based on the head loss diagram (see FIG. 3) of the water heat exchanger 14. The chilling unit 1 specifies a range of the flow rate of water flowing through the water heat exchanger 14, and within this specified flow rate range, a flow rate range is specified according to the site where the chilling unit 1 is installed (specifically, the load, etc.). Therefore, during a trial run, the pump 3 is driven so that the head loss (i.e., P2-P3) obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83 matches the head loss value L2 (see FIG. 3) corresponding to the upper limit of the flow rate range of the water heat exchanger 14 specified for that site (i.e., the operational upper limit flow rate V2). The operating frequency of the pump 3 at this time is then stored in the memory unit 74 as the operational upper limit frequency Fp2 (see FIG. 4).

[0040] (Step S2) Next, the chilling unit 1 drives the pump 3 at the upper limit frequency during operation Fp2, and stores the pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 at this time in correspondence with the upper limit frequency during operation Fp2 in the memory unit 74. The pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 in step S2 of the trial run are referred to as pressure values ​​P11, P12, and P13 to distinguish them from the pressure values ​​P1, P2, and P3 detected by these sensors during operation after the start of operation.

[0041] (Step S3) The chilling unit 1 also automatically adjusts the operating frequency of the pump 3 to match the head loss (i.e., P2-P3) to the operational lower limit flow rate V1 based on the head loss diagram (see FIG. 3) of the water heat exchanger 14. In other words, the pump 3 is driven so that the head loss obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83 matches the head loss value L1 (see FIG. 3) corresponding to the lower limit of the flow rate range of the water heat exchanger 14 specified for that site (i.e., the operational lower limit flow rate V1). The operating frequency of the pump 3 at this time is then stored in the memory unit 74 as the operational lower limit frequency Fp1 (see FIG. 4).

[0042] (Step S4) Next, the chilling unit 1 drives the pump 3 at the lower limit frequency during operation Fp1, and stores the pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 at this time in correspondence with the lower limit frequency during operation Fp1 in the memory unit 74. The pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 in step S4 of the trial run are referred to as pressure values ​​P21, P22, and P23 to distinguish them from the pressure values ​​P1, P2, and P3 detected by these sensors during operation after the start of operation.

[0043] (Step S5) Next, the chilling unit 1 drives the pump 3 at multiple frequencies between the lower operating frequency limit Fp1 and the upper operating frequency limit Fp2. The chilling unit 1 stores in the memory unit 74 the pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 during operation at each operating frequency, in association with the operating frequency of the pump 3. The pressure values ​​detected by the pre-pump pressure sensor 81, inlet pressure sensor 82, and outlet pressure sensor 83 in step S5 of the trial run are referred to as pressure values ​​P31, P32, and P33 to distinguish them from the pressure values ​​P1, P2, and P3 detected by these sensors during operation after the start of operation. The pressure values ​​P31, P32, and P33 each change depending on the operating frequency.

[0044] If a flow meter (not shown) is provided in the on-site water piping section 2b (see FIG. 1) of the water circuit 2 that is provided outside the chilling unit 1, the operating frequency of the pump 3 may be adjusted manually without using the head loss diagram of the water heat exchanger 14. Specifically, in step S1, the operating frequency when the pump 3 is driven so that the flow meter value reaches the operating upper limit flow rate V2 is set as the operating upper limit frequency Fp2. In addition, in step S3, the operating frequency when the pump 3 is driven so that the flow meter value reaches the operating lower limit flow rate V1 is set as the operating lower limit frequency Fp1.

[0045] In this way, before the start of operation when no scale has accumulated in the water heat exchanger 14, a frequency range for the pump 3 corresponding to the estimated flow rate range can be set from the head loss diagram and the pressure values ​​P2 and P3 detected by the inlet pressure sensor 82 and the outlet pressure sensor 83. Furthermore, before the start of operation when no scale has accumulated in the water heat exchanger 14, the pump 3 is driven at a plurality of frequencies, and pressure values ​​at three points - the suction side of the pump 3, between the pump 3 and the water heat exchanger 14, and the water outlet side of the water heat exchanger 14 - are measured and stored in advance at each frequency. The pressure values ​​P21, P22, P23, P31, P32, and P33 are used as judgment criteria for determining and detecting abnormalities around the water heat exchanger 14 and the pump 3 during operation after the start of operation.

[0046] (During operation after the start of operation of the water circulation air conditioning system 100) Fig. 6 is a flowchart showing abnormality determination control for the chilling unit 1 of Fig. 1. Fig. 7 is an explanatory diagram showing the criteria for each abnormality determination by the control device 7 of Fig. 1. The abnormality determination control performed by the control device 7 during operation after the start of operation will be described with reference to Figs. 6 and 7.

[0047] 6, first, it is determined whether the flow rate of water flowing through the water heat exchanger 14 is less than the operating lower limit flow rate V1 (step S101). Here, the flow rate of water flowing through the water heat exchanger 14 is calculated from the differential pressure (P2-P3) between before and after the water heat exchanger 14, i.e., the head loss, obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83, using the characteristics stored in the memory unit 74 (see FIG. 3).

[0048] In step S101, if it is determined that the flow rate of water flowing through the water heat exchanger 14 is less than the lower limit flow rate V1 during operation (step S101; YES), the determination in step S102 is performed. On the other hand, if it is determined that the flow rate of water flowing through the water heat exchanger 14 is equal to or greater than the lower limit flow rate V1 during operation (step S101; NO), the determination in step S105 is performed.

[0049] (Step S102) In step S102, it is determined whether the pressure value P1 on the suction side of the pump 3 detected by the pre-pump pressure sensor 81 is equal to or greater than 0, i.e., whether it is a positive pressure. If it is determined in step S102 that the pressure value P1 is equal to or greater than 0 (step S102; YES), the determination in step S103 is performed. On the other hand, if it is determined in step S102 that the pressure value P1 is less than 0, i.e., a negative pressure (step S102; NO), process A is performed.

[0050] (Step S103) In step S103, it is determined whether the pressure value P3 on the water outlet side of the water heat exchanger 14 detected by the outlet pressure sensor 83 is lower than the pressure value P23 acquired during the trial run (see step S4 in FIG. 5). Here, the pressure value P23 is the detection value of the outlet pressure sensor 83 when the pump 3 is driven during the trial run so that water flows through the water heat exchanger 14 at the operational lower limit flow rate V1, and is stored in the memory unit 74.

[0051] In step S103, if it is determined that the pressure value P3 is lower than the pressure value P23 during the test run (step S103; YES), the determination of step S104 is performed. On the other hand, if it is determined that the pressure value P3 is equal to or greater than the pressure value P23 during the test run (step S103; NO), process B is performed.

[0052] (Step S104) In step S104, it is determined whether the pressure value P2 on the inlet side of the water heat exchanger 14 detected by the inlet pressure sensor 82 is higher than the pressure value P22 acquired during the trial run (see step S4 in FIG. 5). Here, the pressure value P22 is the detection value of the inlet pressure sensor 82 when the pump 3 is driven during the trial run so that water flows through the water heat exchanger 14 at the operational lower limit flow rate V1, and is stored in the memory unit 74.

[0053] In step S104, if it is determined that the pressure value P2 is higher than the pressure value P22 during the trial run (step S104; YES), processing D is performed, and if it is determined that the pressure value P2 is equal to or lower than the pressure value P22 during the trial run (step S104; NO), processing C is performed.

[0054] (Step S105) In step S105, it is determined whether the pressure value P3 is lower than a predetermined lower limit pressure value (for example, half the pressure value P23 during trial operation). If the pressure value P3 is lower than the lower limit pressure value (step S105; YES), it can be assumed that almost no water is flowing through the water heat exchanger 14. Therefore, in this case, regardless of the pressure difference (P2-P3) before and after the water heat exchanger 14, it is determined that the water flow is less than the operating lower limit flow rate V1, and process D is performed. On the other hand, if it is determined in step S105 that the pressure value P3 is equal to or greater than the lower limit pressure value (step S105; NO), the determination in step S106 is performed.

[0055] (Step S106) In step S106, it is determined whether the flow rate of water flowing through the water heat exchanger 14 is equal to or less than the upper limit flow rate V2 during operation. Here, the flow rate of water flowing through the water heat exchanger 14 is determined by calculation or the like using the characteristics (see FIG. 3) stored in the memory unit 74 from the differential pressure (P2-P3) before and after the water heat exchanger 14, i.e., the head loss, obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83.

[0056] In step S106, if it is determined that the flow rate of the water flowing through the water heat exchanger 14 is equal to or less than the upper limit flow rate V2 during operation (step S106; YES), the determination of step S107 is performed. On the other hand, if it is determined that the flow rate of the water flowing through the water heat exchanger 14 exceeds the upper limit flow rate V2 during operation (step S106; NO), the process returns to step S101.

[0057] (Step S107) In step S107, it is determined whether the pressure value P1 on the suction side of the pump 3 detected by the pre-pump pressure sensor 81 is equal to or greater than 0, i.e., whether it is a positive pressure. If it is determined in step S107 that the pressure value P1 is equal to or greater than 0 (step S107; YES), the determination in step S108 is performed. On the other hand, if it is determined in step S107 that the pressure value P1 is less than 0, i.e., a negative pressure (step S107; NO), the process returns to step S101.

[0058] (Step S108) In step S108, it is determined whether the pressure value P3 on the water outlet side of the water heat exchanger 14 detected by the outlet pressure sensor 83 is lower than the pressure value P33 obtained during the test run (see step S5 in FIG. 5 ). Here, the pressure value P33 serving as the determination criterion in step S108 is the detection value of the outlet pressure sensor 83 obtained during the test run in which the pump 3 was driven at the same frequency as the current operating frequency, and is stored in the memory unit 74. Note that the pressure values ​​P33 obtained by driving the pump 3 at multiple operating frequencies during the test run may be stored in the memory unit 74 as a function of the operating frequency of the pump 3. In this case, the pressure value P33 serving as the determination criterion in step S108 is obtained by calculation from the operating frequency of the pump 3 in the current operation.

[0059] In step S108, if it is determined that the pressure value P3 is lower than the pressure value P33 during the test run (step S108; YES), the determination of step S109 is performed. On the other hand, in step S108, if it is determined that the pressure value P3 is equal to or greater than the pressure value P33 during the test run (step S108; NO), the process returns to step S101.

[0060] (Step S109) In step S109, it is determined whether the pressure value P2 on the inlet side of the water heat exchanger 14 detected by the inlet pressure sensor 82 is higher than the pressure value P32 obtained during the test run (see step S5 in FIG. 5 ). Here, the pressure value P32 serving as the determination criterion in step S109 is the detection value of the inlet pressure sensor 82 obtained during the test run in which the pump 3 was driven at the same frequency as the current operating frequency, and is stored in the memory unit 74. Note that the pressure values ​​P32 obtained by driving the pump 3 at multiple operating frequencies during the test run may be stored in the memory unit 74 as a function of the operating frequency of the pump 3. In this case, the pressure value P32 serving as the determination criterion in step S109 is obtained by calculation from the operating frequency of the pump 3 in the current operation.

[0061] In step S109, if it is determined that the pressure value P2 is higher than the pressure value P32 during the test run (step S109; YES), process E is performed. On the other hand, in step S109, if it is determined that the pressure value P2 is equal to or lower than the pressure value P32 during the test run (step S109; NO), the process returns to step S101.

[0062] Processes A to E will be described below with reference to Figures 6 and 7. In the table of Figure 7, for each of Processes A to E, the change in each parameter (pressure value or differential pressure) when the process is reached is indicated by an arrow. The change in each parameter is the result of comparing the value of that parameter during trial operation and during operation, with an upward arrow indicating that the value of that parameter is larger (i.e., increased) during operation compared to trial operation, and a downward arrow indicating that the value of that parameter is smaller (i.e., decreased) during operation compared to trial operation.

[0063] 6 and 7, in the above-described abnormality determination control, if the flow rate calculated from the head loss (i.e., P2-P3) is less than the lower limit flow rate V1 during operation and the pressure value P1 on the water intake side of the pump 3 is negative, process A is performed. In process A, it is determined that the negative pressure on the water intake side of the pump 3 has caused the water flow rate of the water heat exchanger 14 to fall below the lower limit flow rate V1 during operation, and this is output as the result of the abnormality determination to the alarm unit 99. In addition to the result of this abnormality determination, information on how to deal with this abnormality, such as "Increase the pressure on the water intake side of the pump" or "Remove any resistance on the water intake side of the pump," is also output to the alarm unit 99.

[0064] Also, as shown in Figure 7, when the water intake side of the pump 3 is under negative pressure, the pressure value P2 on the water inlet side of the water heat exchanger 14 and the pressure value P3 on the water outlet side of the water heat exchanger 14 are lower than the pressure values ​​P22 and P23 during trial operation when the water flow is set to the lower limit flow rate V1 during operation.

[0065] 6 and 7, in the above-described abnormality determination control, if the flow rate calculated from the head loss (i.e., P2-P3) is less than the lower limit flow rate V1 during operation, the pressure value P1 on the water intake side of the pump 3 is positive, and the pressure value P3 on the water outlet side of the water heat exchanger 14 is higher than the pressure value P23 during trial operation when the water flow is set to the lower limit flow rate V1, then process B is performed. In process B, it is determined that a blockage has occurred downstream of the water discharge side of the pump 3 (for example, in the on-site water piping section 2b on the water outlet side of the chilling unit 1), and a message to that effect is output to the alarm section 99 as the result of the abnormality determination.

[0066] 7, when a blockage occurs downstream of the water discharge side of the pump 3 in the water circuit 2, the head of the pump 3 (i.e., P2-P1) increases compared to the head during trial operation (P22-P21) in an attempt to compensate for the decrease in flow rate of the water heat exchanger 14. Accordingly, the pressure value P2 on the water inlet side of the water heat exchanger 14 also increases compared to the pressure value P22 during trial operation when the water flow is set to the operational lower limit flow rate V1.

[0067] 6 and 7, in the above-described abnormality determination control, if the flow rate calculated from the head loss (i.e., P2-P3) is less than the lower limit flow rate V1 during operation, the pressure value P1 on the water intake side of the pump 3 is positive, the pressure value P3 on the water outlet side of the water heat exchanger 14 is lower than the pressure value P23 during trial operation when the water flow was set to the lower limit flow rate V1, and the pressure value P2 on the water inlet side of the water heat exchanger 14 is lower than the pressure value P22 during trial operation when the water flow was set to the lower limit flow rate V1, then process C is performed. In process C, it is determined that the water flow rate of the water heat exchanger 14 has fallen below the lower limit flow rate V1 due to air entrapment inside the pump 3, and this fact is output to the alarm unit 99 as the result of the abnormality determination.

[0068] Furthermore, as shown in FIG. 7, when air entrapment occurs inside the pump 3, the head of the pump 3 (i.e., P2-P1) is reduced compared to the head during trial operation (P22-P21).

[0069] 6 and 7, in the above-described abnormality determination control, if the flow rate calculated from the head loss (i.e., P2-P3) is less than the lower limit operation flow rate V1, the pressure value P1 on the water intake side of the pump 3 is positive, the pressure value P3 on the water outlet side of the water heat exchanger 14 is lower than the pressure value P23 during trial operation when the water flow was set to the lower limit operation flow rate V1, and the pressure value P2 on the water inlet side of the water heat exchanger 14 is higher than the pressure value P22 during trial operation when the water flow was set to the lower limit operation flow rate V1, then process D is performed. In process D, it is determined that the water flow rate of the water heat exchanger 14 has fallen below the lower limit operation flow rate V1 due to internal freezing of the water heat exchanger 14, and this information is output to the alarm unit 99 as the result of the abnormality determination.

[0070] Furthermore, as shown in FIG. 7, when the water heat exchanger 14 is internally frozen, the pressure difference (P2-P1) across the pump 3 increases compared to the head (P22-P21) during trial operation.

[0071] Furthermore, in the abnormality determination control of FIG. 6 , even if the flow rate calculated from the differential pressure (P2-P3) across the water heat exchanger 14 in step S101 is equal to or greater than the operational lower limit flow rate V1, if the pressure value P3 on the water outlet side of the water heat exchanger 14 in step S105 is less than the lower limit pressure value (half the pressure value P23 during trial operation when the water flow is set to the operational lower limit flow rate V1), process D is performed. This is because even if the flow rate calculated from the differential pressure (P2-P3) across the water heat exchanger 14 is equal to or greater than the operational lower limit flow rate V1, the water flow path may actually be narrowed due to internal freezing of the water heat exchanger 14, resulting in the flow rate being less than the operational lower limit flow rate V1. In this case, because the pressure value P3 is less than the lower limit pressure value, the differential pressure (P2-P3) across the water heat exchanger 14 increases compared to the head loss (P22-P23) during trial operation when the water flow is set to the operational lower limit flow rate V1, as shown in FIG. 7 .

[0072] 6 and 7, in the above-described abnormality determination control, if the flow rate calculated from the head loss (i.e., P2-P3) is equal to or greater than the lower limit flow rate V1 during operation and equal to or less than the upper limit flow rate V2 during operation, the pressure value P1 on the water intake side of the pump 3 is positive, the pressure value P3 on the water outlet side of the water heat exchanger 14 is lower than the pressure value P33 during trial operation at the same operating frequency, and the pressure value P2 on the water inlet side of the water heat exchanger 14 is higher than the pressure value P32 during trial operation at the same operating frequency, then process E is performed. In other words, if the flow rate calculated from the head loss (i.e., P2-P3) is within the specified flow rate range, but the pressure value P2 on the water inlet side of the water heat exchanger 14 is higher and the pressure value P3 on the water outlet side of the water heat exchanger 14 is lower than the pressure values ​​P32 and P33 during trial operation when the pump 3 is driven at the same frequency as the current operating frequency, then process E is performed. In process E, it is determined that scale or other contaminants have formed in the water flow path of the water heat exchanger 14, and this is output as an abnormality determination result to the alarm unit 99. Along with this abnormality determination result, information on how to deal with this abnormality, such as "Please clean the water heat exchanger," is also output to the alarm unit 99. In order to more accurately distinguish between a case where internal freezing of the water heat exchanger 14 has occurred (when process D is performed) and a case where scale has formed in the water flow path of the water heat exchanger 14 (when process E is performed), process D and process E may be further distinguished based on the water temperature in the water flow path of the water heat exchanger 14 or the accumulated operating time. In this case, the water heat exchanger 14 is provided with a temperature sensor that detects the water temperature in the water flow path.

[0073] 7, when the water flow path of the water heat exchanger 14 is dirty, the pressure difference (P2-P3) across the water heat exchanger 14 increases compared to the head loss (P32-P33) during trial operation at the same operating frequency. Also, the pressure difference (P2-P1) across the pump 3 increases compared to the head (P32-P31) during trial operation.

[0074] Of the above processes A to E, in processes A to D, where the flow rate falls outside a predetermined flow rate range, control such as stopping operation may be performed. On the other hand, in process E, where the flow rate is within a predetermined flow rate range, abnormality information may be output to the alarm unit 99, but operation may continue. When internal freezing of the water heat exchanger 14 occurs (when process D is performed) and when scale forms in the water flow path of the water heat exchanger 14 (when process E is performed), the trends in the pressure values ​​P2 and P3 are similar, but the progress of internal freezing is faster than the increase in scale. Therefore, when internal freezing occurs, the flow rate falls below the operational lower limit flow rate V1 in a shorter time than when scale forms, and the water flow drops sharply, causing the pressure value P3 to fall below the lower limit pressure value (half the pressure value P23 during trial operation), for example.

[0075] In the above embodiment, the chilling unit 1 has been described as an example in which the water heat exchanger 14 is the evaporator of the refrigerant circuit 10 and the chilling unit 1 uses the heat of a heat-source refrigerant such as chlorofluorocarbon to cool water to a target temperature. However, the chilling unit 1 may be configured so that the refrigerant circuit 10 includes a four-way valve and the chilling unit 1 can not only cool water to a target temperature but also heat water to a target temperature using the heat of a heat-source refrigerant such as chlorofluorocarbon. Also, while Figure 1 shows a configuration in which the refrigerant in the refrigerant flow path and the water in the water flow path flow in countercurrent flow in the water heat exchanger 14, they may also flow in parallel.

[0076] In addition, although the heat medium flowing through the water circuit 2 has been described as being water, it is possible to use not only water but also brine as the heat medium by changing the information on the physical properties of the heat medium. For example, by configuring the control device 7 to calculate the head loss diagram of the water heat exchanger 14 from the type and concentration of brine, the system can be operated in the same way as when water is used, even when brine is used.

[0077] As described above, the chilling unit 1 constitutes part of the heat medium circuit (water circuit 2) and comprises a heat medium piping section (water piping section 2a) through which the heat medium flows, a refrigerant circuit 10 having a compressor 11 that compresses the refrigerant and through which the refrigerant is circulated by the compressor 11, and a heat medium heat exchanger (water heat exchanger 14) that exchanges heat between the heat medium and the refrigerant. The heat medium heat exchanger (water heat exchanger 14) has a heat medium flow path through which the heat medium flows and a refrigerant flow path through which the refrigerant flows, and is provided in the heat medium piping section (water piping section 2a) and constitutes part of the heat medium circuit and refrigerant circuit 10. The chilling unit 1 also comprises a pump 3 provided upstream of the heat medium heat exchanger in the heat medium piping section and that delivers the heat medium to the heat medium heat exchanger, and a pre-pump pressure sensor 81 that detects the heat medium pressure on the suction side of the pump 3. The chilling unit 1 also includes an inlet pressure sensor 82 that is on the discharge side of the pump 3 and detects the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger (water heat exchanger 14), and an outlet pressure sensor 83 that detects the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger.

[0078] In this way, chilling unit 1 is provided with water pressure sensors on the suction side of the pump and on the heat medium inlet and outlet sides of the heat medium heat exchanger, making it possible to distinguish between abnormalities around the heat medium heat exchanger and abnormalities around the pump. If an alarm unit 99 or the like is configured to notify abnormality information, the worker performing the periodic inspection can refer to the notified abnormality information and take action or check the necessary areas, so the area to be taken care of or checked can be narrowed compared to conventional methods, leading to a reduction in work time.

[0079] The chilling unit 1 also includes a control device 7 that detects abnormalities in the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14) based on the heat medium pressure (pressure value P1) on the suction side of the pump 3 detected by a pre-pump pressure sensor 81, the heat medium pressure (pressure value P2) on the heat medium inlet side of the heat medium heat exchanger detected by an inlet pressure sensor 82, and the heat medium pressure (pressure value P3) on the heat medium outlet side of the heat medium heat exchanger detected by an outlet pressure sensor 83.

[0080] Furthermore, when the flow rate of the heat medium calculated from the pressure difference (P2-P3) between the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger is less than a predetermined lower limit flow rate V1 during operation, and when the heat medium pressure (pressure value P1) at the suction side of the pump 3 is negative pressure, the control device 7 determines that the cause is upstream of the pump 3.

[0081] Therefore, when the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14) is less than the lower limit flow rate V1 during operation, it can be determined that the cause is not only inside the water heat exchanger 14 or the pump 3 in the water circuit 2, but also upstream of the pump 3.

[0082] The control device 7 also stores the heat medium pressure (pressure value P21) on the suction side of the pump 3, the heat medium pressure (pressure value P22) on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure (pressure value P23) on the heat medium outlet side of the heat medium heat exchanger when the pump 3 is driven at a predetermined lower limit frequency Fp1 during a trial run before the start of operation. Then, when the flow rate of the heat medium calculated from the pressure difference (P2-P3) between the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger and the heat medium pressure (pressure value P3) on the heat medium outlet side of the heat medium heat exchanger becomes less than the predetermined lower limit flow rate V1 during operation after the start of operation, the control device 7 calculates the heat medium pressure (pressure value P1) on the suction side of the pump 3, the heat medium pressure (pressure value P2) on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure (pressure value P2) on the heat medium outlet side of the heat medium heat exchanger. The heat medium pressure (pressure value P3) at the intake side of the pump 3 when the pump 3 is driven at the lower limit operating frequency Fp1 during a trial run is compared with the heat medium pressure (pressure value P21) at the intake side of the pump 3, the heat medium pressure (pressure value P22) at the intake side of the heat medium heat exchanger, and the heat medium pressure (pressure value P23) at the outlet side of the heat medium heat exchanger. In other words, by comparing the pressure value P1 with the pressure value P21, the pressure value P2 with the pressure value P22, and the pressure value P3 with the pressure value P23, the cause of the heat medium flow rate being less than the lower limit operating flow rate V1 can be determined.

[0083] Compared to the conventional configuration, the addition of the pre-pump pressure sensor 81 makes it possible to detect the heat medium pressure (pressure values ​​P1, P21) on the suction side of the pump 3 and to calculate the differential pressure (P2-P1) before and after the pump 3, i.e., the head. Therefore, the number of parameters that can be used to determine an abnormality has increased, making it possible to distinguish the cause in more detail.

[0084] If, during operation, the calculated flow rate of the heat medium becomes less than the operating lower limit flow rate V1, the heat medium pressure (pressure value P1) on the suction side of the pump 3 is positive, and the heat medium pressure (pressure value P3) on the heat medium outlet side of the heat medium heat exchanger is higher than the heat medium pressure (P23) on the heat medium outlet side of the heat medium heat exchanger when the pump is driven at the operating lower limit frequency Fp1 during trial operation, the control device 7 determines that there is a cause downstream of the heat medium heat exchanger that causes the heat medium flow rate to become less than the operating lower limit flow rate V1.

[0085] Therefore, when the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14) is less than the lower limit flow rate V1 during operation, it can be determined that the cause is not only inside the water heat exchanger 14 or the pump 3 in the water circuit 2, but also downstream of the water heat exchanger 14.

[0086] Furthermore, if the calculated flow rate of the heat medium during operation becomes less than the lower limit operational flow rate V1, and if the heat medium pressure (pressure value P1) on the suction side of the pump 3 is positive and the heat medium pressure (pressure value P2) on the heat medium inlet side of the heat medium heat exchanger is lower than the heat medium pressure (pressure value P22) on the heat medium inlet side of the heat medium heat exchanger when the pump is driven at the lower limit operational frequency Fp1 during trial operation, the control device 7 determines that the cause of the heat medium flow rate becoming less than the lower limit operational flow rate is within the pump 3.

[0087] Therefore, when the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14) falls below the lower limit flow rate V1 during operation, it is possible to distinguish between the cause being the heat medium heat exchanger and the cause being air trapped inside the pump 3 upstream of the heat medium heat exchanger.

[0088] During operation, if the calculated flow rate of the heat medium becomes less than the operating lower limit flow rate V1, and if the heat medium pressure (pressure value P1) on the suction side of the pump 3 is positive and the heat medium pressure (pressure value P2) on the heat medium inlet side of the heat medium heat exchanger is higher than the heat medium pressure (pressure value P22) on the heat medium inlet side of the heat medium heat exchanger when the pump is driven at the operating lower limit frequency Fp1 during trial operation, the control device 7 determines that the flow rate of the heat medium has become less than the operating lower limit flow rate V1 due to internal freezing of the heat medium heat exchanger.

[0089] Therefore, when the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14) is less than the operational lower limit flow rate V1, it can be determined that the cause is internal freezing of the heat medium heat exchanger, distinguishing it from cases where the cause is the pump 3. Here, the abnormality determination result may be fed back to the control of the compressor 11, etc. For example, when it is determined that the cause of the decrease in the flow rate of the heat medium in the heat medium heat exchanger is internal freezing of the heat medium heat exchanger, it is advisable to adjust the operating frequency of the compressor 11 so that the temperature of the water heat exchanger 14 increases.

[0090] The control device 7 also stores the heat medium pressure (pressure value P31) on the suction side of the pump 3, the heat medium pressure (pressure value P32) on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure (pressure value P33) on the heat medium outlet side of the heat medium heat exchanger when the pump 3 is driven at a plurality of frequencies during a trial run before the start of operation.The control device 7 then calculates, during operation after the start of operation, a flow rate of the heat medium calculated from the differential pressure (P2-P3) between the heat medium pressure (pressure value P2) on the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure (pressure value P3) on the heat medium outlet side of the heat medium heat exchanger, and the heat medium pressure (pressure value P3) on the heat medium outlet side of the heat medium heat exchanger, within a predetermined flow rate range during operation. When the heat medium pressure (pressure value P2) at the heat medium inlet side of the heat medium heat exchanger during a trial run with the pump frequency set to the same as that during operation (pressure value P32) increases compared to the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger during a trial run with the pump frequency set to the same as that during operation (pressure value P3), and when the heat medium pressure (pressure value P3) at the heat medium outlet side of the heat medium heat exchanger decreases compared to the heat medium pressure (pressure value P33) at the heat medium outlet side of the heat medium heat exchanger during a trial run with the pump frequency set to the same as that during operation, it is determined that contamination has occurred inside the heat medium heat exchanger.

[0091] This makes it possible to detect a situation in which the flow rate of the heat medium in the heat medium heat exchanger (water heat exchanger 14) has not yet fallen below the operational lower limit flow rate V1 but has decreased from the level during trial operation due to the formation of scale. Incidentally, if scale accumulates in the water flow path of the water heat exchanger 14, the scale may impede heat exchange between the water and the refrigerant, thereby reducing the coefficient of performance (COP) of the chilling unit 1. Therefore, it is preferable to configure the system to issue an alert regarding scale in the water heat exchanger 14 before the flow rate falls below the operational lower limit flow rate V1, and to maintain a clear water flow path during operation, i.e., maintain good heat exchange efficiency, by taking measures such as cleaning.

[0092] The chilling unit 1 also includes a notification unit 99 that notifies the user of abnormality information when the control device 7 detects an abnormality in the flow rate of the heat medium flowing through the heat medium heat exchanger (water heat exchanger 14). This allows, for example, a worker performing a periodic inspection to check the abnormality information notified by the notification unit 99 and learn about abnormalities in the water flow occurring around the water heat exchanger 14 and the pump 3, as well as information about the abnormality (for example, the location where the abnormality occurred).

[0093] 1 Chilling unit, 2 Water circuit, 2a Water piping section, 2b On-site water piping section, 3 Pump, 4 Load side heat exchanger, 6 Remote control, 7 Control device, 10 Refrigerant circuit, 11 Compressor, 12 Heat source side heat exchanger, 13 Throttle device, 14 Water heat exchanger, 15 Blower fan, 71 Input section, 72 Calculation section, 73 Control section, 74 Memory section, 81 Pre-pump pressure sensor, 82 Inlet pressure sensor, 83 Outlet pressure sensor, 99 Notification section, 100 Water circulation air conditioning system, A, B, C, D, E Processing, C1, C2, C3 Pump head curve, Fp1 Lower limit frequency during operation, Fp2 Upper limit frequency during operation, Fp3 Rated frequency, L1 Head loss value, L2 Head loss value, P1, P11, P12, P13, P2, P21, P22, P23, P3, P31, P32, P33 pressure value, V1 lower limit flow rate during operation, V2 upper limit flow rate during operation.

Claims

1. A heat medium pipe section that forms part of a heat medium circuit and through which the heat medium flows, A refrigerant circuit having a compressor that compresses the refrigerant and through which the refrigerant circulates by the compressor, A heat medium heat exchanger that has a heat medium flow path through which the heat medium flows and a refrigerant flow path through which the refrigerant flows, is provided in the heat medium pipe section, and forms part of the heat medium circuit and the refrigerant circuit, and that performs heat exchange between the heat medium and the refrigerant, A pump provided upstream of the heat medium heat exchanger in the heat medium pipe section for sending the heat medium to the heat medium heat exchanger, A pump pre-pressure sensor that detects the heat medium pressure on the suction side of the pump, An inlet pressure sensor that is on the discharge side of the pump and detects the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger, An outlet pressure sensor that detects the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger, A control device that detects an abnormality in the flow rate of the heat medium flowing through the heat medium heat exchanger based on the heat medium pressure on the suction side of the pump detected by the pump pre-pressure sensor, the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger detected by the inlet pressure sensor, and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger detected by the outlet pressure sensor, When the flow rate of the heat medium calculated from the differential pressure between the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger is less than a predetermined lower limit flow rate during operation, and when the heat medium pressure on the suction side of the pump is negative pressure, the control device determines that the cause is upstream of the pump Chilling unit.

2. A heat medium pipe section that forms part of a heat medium circuit and through which the heat medium flows, A refrigerant circuit having a compressor that compresses the refrigerant and through which the refrigerant circulates by the compressor, A heat medium heat exchanger that has a heat medium flow path through which the heat medium flows and a refrigerant flow path through which the refrigerant flows, is provided in the heat medium pipe section, and forms part of the heat medium circuit and the refrigerant circuit, and that performs heat exchange between the heat medium and the refrigerant, A pump provided upstream of the heat medium heat exchanger in the heat medium pipe section for sending the heat medium to the heat medium heat exchanger, A pump pre-pressure sensor that detects the heat medium pressure on the suction side of the pump, An inlet pressure sensor that is on the discharge side of the pump and detects the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger; An outlet pressure sensor that detects the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger; A control device that detects an abnormality in the flow rate of the heat medium flowing through the heat medium heat exchanger based on the heat medium pressure on the suction side of the pump detected by the pump pre-pressure sensor, the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger detected by the inlet pressure sensor, and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger detected by the outlet pressure sensor; The control device stores the heat medium pressure on the suction side of the pump, the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger in each case where the pump is driven at a plurality of frequencies during a trial operation before the start of operation; During operation after the start of operation, the control device calculates the differential pressure between the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger, and the flow rate of the heat medium calculated from the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger. When within a predetermined flow rate range during operation, if the heat medium pressure on the suction side of the pump is a positive pressure, the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger rises compared to the heat medium pressure at the heat medium inlet side of the heat medium heat exchanger during the trial operation with the same pump frequency as in the case during operation, and the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger is lower compared to the heat medium pressure at the heat medium outlet side of the heat medium heat exchanger during the trial operation with the same pump frequency as in the case during operation, it is determined that dirt has occurred inside the heat medium heat exchanger; Chilling unit.

3. A heat medium piping section that forms part of a heat medium circuit and through which a heat medium flows; A refrigerant circuit having a compressor that compresses a refrigerant and through which the refrigerant circulates by the compressor; A heat medium heat exchanger that has a heat medium flow path through which the heat medium flows and a refrigerant flow path through which the refrigerant flows, is provided in the heat medium piping section, forms part of the heat medium circuit and the refrigerant circuit, and performs heat exchange between the heat medium and the refrigerant; A pump provided upstream of the heat medium heat exchanger in the heat medium piping section for delivering the heat medium to the heat medium heat exchanger, A pump inlet pressure sensor for detecting the heat medium pressure on the suction side of the pump, An inlet pressure sensor that is on the discharge side of the pump and detects the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger, An outlet pressure sensor for detecting the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger, Based on the heat medium pressure on the suction side of the pump detected by the pump inlet pressure sensor, the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger detected by the inlet pressure sensor, and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger detected by the outlet pressure sensor, a control device for detecting an abnormality in the flow rate of the heat medium flowing through the heat medium heat exchanger, The control device stores the heat medium pressure on the suction side of the pump, the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger when the pump is driven at a predetermined lower limit operating frequency during a trial operation before the start of operation. When the differential pressure between the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger during operation after the start of operation, and the flow rate of the heat medium calculated from the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger are less than a predetermined lower limit flow rate during operation, the control device determines the cause of the flow rate of the heat medium being less than the lower limit flow rate during operation by comparing the heat medium pressure on the suction side of the pump during operation, the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger with the heat medium pressure on the suction side of the pump, the heat medium pressure on the heat medium inlet side of the heat medium heat exchanger, and the heat medium pressure on the heat medium outlet side of the heat medium heat exchanger when the pump was driven at the lower limit operating frequency during the trial operation. Chilling unit.

4. When the calculated flow rate of the heat medium becomes less than the lower limit flow rate during operation, if the pressure of the heat medium on the suction side of the pump is a positive pressure and the pressure of the heat medium on the heat medium outlet side of the heat medium heat exchanger has increased as compared with the pressure of the heat medium on the heat medium outlet side of the heat medium heat exchanger when the pump was driven at the lower limit frequency during the trial operation, the control device determines that there is a cause for the flow rate of the heat medium to become less than the lower limit flow rate downstream of the heat medium heat exchanger. The chiller unit according to claim 3.

5. When the calculated flow rate of the heat medium becomes less than the lower limit flow rate during operation, if the pressure of the heat medium on the suction side of the pump is a positive pressure and the pressure of the heat medium on the heat medium inlet side of the heat medium heat exchanger has decreased as compared with the pressure of the heat medium on the heat medium inlet side of the heat medium heat exchanger when the pump was driven at the lower limit frequency during the trial operation, the control device determines that there is a cause for the flow rate of the heat medium to become less than the lower limit flow rate inside the pump. The chiller unit according to claim 3 or 4.

6. When the calculated flow rate of the heat medium becomes less than the lower limit flow rate during operation, if the pressure of the heat medium on the suction side of the pump is a positive pressure and the pressure of the heat medium on the heat medium inlet side of the heat medium heat exchanger has increased as compared with the pressure of the heat medium on the heat medium inlet side of the heat medium heat exchanger when the pump was driven at the lower limit frequency during the trial operation, the control device determines that the flow rate of the heat medium has become less than the lower limit flow rate due to internal freezing of the heat medium heat exchanger. The chiller unit according to claim 3 or 4.

7. Comprising a notification unit that notifies abnormal information of the abnormality when the abnormality of the flow rate of the heat medium flowing through the heat medium heat exchanger is detected by the control device. The chiller unit according to any one of claims 1 to 4.