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

Title of Invention CHILLING UNIT Technical Field

[0001] The present disclosure relates to a chiller unit provided with a water pressure sensor. Background Art

[0002] A chiller unit is used as a heat source device of a water-circulating air-conditioning system that circulates water in a structure and is used for, for example, a building or a large commercial facility. The chiller unit has a refrigerant circuit through which refrigerant circulates and a portion of a water circuit that circulates water, which is a heat medium, in the structure. The chiller unit transports heat through the water circuit to load-side equipment (such as a fan-coil unit and an airhandling unit), and uses the heat for cooling and heating a compartment. The refrigerant circuit has a compressor that compresses refrigerant whereas the water circuit has a pump that pumps water. In such a chiller unit, it is effective to use a compressor and a pump that are compatible with inverters. To enable inverter control of the compressor and the pump, the temperature of water is measured and optimal control is applied according to the load. In the chiller unit, the flow rate of water is adjusted according to the load. When the load is small, the flow rate of water is reduced, the power required to transport the water is reduced, and energy savings are thereby achieved. Among the chiller units each provided with a pump that changes the flow rate of water as described above, there is one provided with water pressure sensors at the respective water inlet and water outlet of a water heat exchanger, which is a heat-medium heat exchanger that allows refrigerant and water to exchange heat with each other (see, for example, Patent Literature 1).

[0003] The chiller unit disclosed in Patent Literature 1 is configured to estimate the flow rate of water that flows through the water heat exchanger from the difference in water pressure at the water inlet and the water outlet of the water heat exchanger and to control the pump such that the estimated flow rate is maintained at or above the lower operating flow rate limit determined by pump characteristics and thereby prevents the interior of the water heat exchanger from freezing. Citation List Patent Literature

[0004] Patent Literature 1: Japanese Patent No. 6570746 Summary of Invention Technical Problem

[0005] However, as in the chiller unit disclosed in Patent Literature 1, with a structure provided with water pressure sensors at only two positions, which are one between the pump and the water inlet of the water heat exchanger and the other at the water outlet side of the water heat exchanger, it is difficult to distinguish between an abnormality around the water heat exchanger and another abnormality around the pump.

[0006] The present disclosure aims to solve the above problem and an object of the present disclosure is to provide a chiller unit configured to detect and distinguish between an abnormality around the water heat exchanger (heat-medium heat exchanger) and an abnormality around the pump. Solution to Problem

[0007] A chiller unit according to an embodiment of the present disclosure is provided with a heat-medium piping section that forms a portion of a heat-medium circuit and through which a heat medium flows; a refrigerant circuit that has a compressor configured to compress refrigerant and through which the refrigerant circulates by the compressor; a heat-medium heat exchanger that has a heat-medium passage through which the heat medium flows and a refrigerant flow passage through which the refrigerant flows, is provided at the heat-medium piping section, and forms a portion of the heat-medium circuit and a portion of the refrigerant circuit, the heatmedium heat exchanger allowing the heat medium and the refrigerant to exchange heat with each other; a pump provided upstream of the heat-medium heat exchanger of the heat-medium piping section and configured to deliver the heat medium to the heat-medium heat exchanger; a pump suction pressure sensor configured to detect heat medium pressure at a suction side of the pump; an inlet pressure sensor configured to detect heat medium pressure at a discharge side of the pump and at a heat-medium inlet side of the heat-medium heat exchanger; and an outlet pressure sensor configured to detect heat medium pressure at a heat-medium outlet side of the heat-medium heat exchanger. Advantageous Effects of Invention

[0008] A chiller unit according to an embodiment of the present disclosure is provided with water pressure sensors at respective positions, which are one at the suction side of a pump, another at the heat-medium inlet side of a heat-medium heat exchanger, and the other at the heat-medium outlet side of the heat-medium heat exchanger and is thereby configured to detect and distinguish between an abnormality around the heat-medium heat exchanger and an abnormality around the pump. Brief Description of Drawings

[0009] [Fig. 1] Fig. 1 is a circuit diagram that illustrates a schematic configuration of a water-circulating air-conditioning system provided with a chiller unit, as a heat source device, according to an embodiment of the present disclosure. [Fig. 2] Fig. 2 is a block diagram that illustrates functions of a controller illustrated in Fig. 1. [Fig. 3] Fig. 3 is a diagram that illustrates the relationship between the water head loss and the flow rate at a water heat exchanger illustrated in Fig. 1. [Fig. 4] Fig. 4 is a diagram that illustrates the relationship between the head and the flow rate at a pump illustrated in Fig. 1. [Fig. 5] Fig. 5 is a flowchart that illustrates control during a trial operation of the chiller unit illustrated in Fig. 1. [Fig. 6] Fig. 6 is a flowchart that illustrates abnormality determination control of the chiller unit illustrated in Fig. 1. [Fig. 7] Fig. 7 is an explanatory diagram that illustrates criteria for determination of each abnormality by the controller illustrated in Fig. 1. Description of Embodiments

[0010] An embodiment of the present disclosure is described below with reference to drawings. Note that elements given the same reference signs in each drawing are the same or equivalent elements and these reference signs are common throughout the whole text of the specification. Furthermore, the forms of components described in the whole text of the specification are merely illustrative and are not limited to these described forms.

[0011] Embodiment Fig. 1 is a circuit diagram that illustrates a schematic configuration of a water-circulating air-conditioning system provided with a chiller unit, as a heat source device, according to an embodiment of the present disclosure. In the embodiment, a heatmedium circulation system is described with a water-circulating air-conditioning system 100 taken as an example. The water-circulating air-conditioning system 100 is provided with a chiller unit 1 and a water circuit 2, a portion of which is located in the chiller unit 1. Water that circulates 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. Note that brine may also be used as the heat medium. In Fig. 1, the directions in which water flows are indicated by solid arrows.

[0012] The chiller unit 1 is provided with a refrigerant circuit 10, a portion of the water circuit 2, and a controller 7. The portion of the water circuit 2 provided in the chiller unit 1 is formed by a water piping section 2a and a pump 3 and other components provided in the water piping section 2a. The water piping section 2a corresponds to the heat-medium piping section of the present disclosure. The refrigerant circuit 10 of the chiller unit 1 is formed by connecting a compressor 11, a heat source-side heat exchanger 12, an expansion device 13, and a water heat exchanger 14 with pipes such that refrigerant circulates.

[0013] The compressor 11 compresses refrigerant, which is heat source-side refrigerant such as a fluorocarbon. Inverter control of the compressor 11 is performed by the controller 7. The heat source-side heat exchanger 12 allows refrigerant to exchange heat with air such as outdoor air. Adjacent to the heat source-side heat exchanger 12, an air-sending fan 15, which sends air to the heat source-side heat exchanger 12, is provided. Inverter control of the air-sending fan 15 is performed by the controller 7. The expansion device 13 adjusts the pressure of refrigerant. The opening and closing of the expansion device 13 is controlled by the controller 7. As the expansion device 13, a linear expansion valve (LEV) or another valve capable of adjusting its opening degree may be used. However, as the expansion device 13, a capillary tube, which is not capable of adjusting its opening degree, may also be used. The water heat exchanger 14 allows refrigerant to exchange heat with water, which is different from the refrigerant. The water heat exchanger 14 cools water in the water circuit 2 by the heat of refrigerant to a target temperature. The water heat exchanger 14 has a refrigerant flow passage through which refrigerant flows and a water flow passage through which water flows. The water heat exchanger 14 forms a portion of the refrigerant circuit 10 and a portion of the water circuit 2. The water heat exchanger 14 is, for example, a plate heat exchanger, and is structured such that the refrigerant flow passage and the water flow passage alternately overlap and thereby directly exchange heat. The water heat exchanger 14 corresponds to the heat-medium heat exchanger of the present disclosure. Also, the water flow passage corresponds to the heat-medium passage of the present disclosure.

[0014] Note that, as refrigerant that flows through the refrigerant circuit 10, for example, a single-component refrigerant such as R-22 and R-134a, a near-azeotropic refrigerant mixture such as R-410Aand R-404A, and a zeotropic refrigerant mixture such as R-407C may be used. Also, a refrigerant or its mixture that contains a double bond in its chemical formula, such as CF3CF=CH2, which is considered to have relatively low global warming potential, as well as a natural refrigerant such as CO2 and propane, may be used.

[0015] The water circuit 2 is formed by connecting the chiller unit 1 and a load-side heat exchanger 4 with pipes such that water circulates. Specifically, the water circuit 2 is formed by connecting the pump 3, the water flow passage of the water heat exchanger 14, and the load-side heat exchanger 4 with pipes. The pump 3 of the chiller unit 1 circulates, through the water circuit 2, water used for heat exchange of the water heat exchanger 14. Inverter control of the pump 3 is performed by the controller 7.

[0016] The load-side heat exchanger 4 is, for example, a fan-coil unit or an airhandling unit provided in a structure and cools indoor air by use of water in the water circuit 2.

[0017] The controller 7 is formed by dedicated hardware or a central processing unit (CPU) that executes a program stored in a memory. Note that the CPU is also referred to as a central processor, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, ora processor.

[0018] In a case where the controller 7 is dedicated hardware, the controller 7 corresponds to, for example, a single circuit, a composite circuit, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of these components listed above. Functions performed by the controller 7 may also be performed by respective pieces of hardware. Alternatively, all the functions may also be performed by a single piece of hardware.

[0019] In a case where the controller 7 is a CPU, functions performed by the controller 7 are performed by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in a memory. The CPU reads out and executes programs stored in the memory and performs the functions of the controller 7. Here, the memory is, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and an EEPROM.

[0020] Part of the functions of the controller 7 may also be performed by dedicated hardware while another part may also be performed by software or firmware.

[0021] Note that the controller 7 illustrated in Fig. 1 is provided in the chiller unit 1 in the water-circulating air-conditioning system 100; however, the controller 7 is not limited to this arrangement and may also be provided outside the chiller unit 1.

[0022] Also, the water-circulating air-conditioning system 100 is provided with various sensors. Specifically, the chiller unit 1 is provided with sensors such as a pump suction pressure sensor 81 provided at the water suction side of the pump 3, which pumps water into the water heat exchanger 14, an inlet pressure sensor 82 provided between the pump 3 and the water heat exchanger 14, that is, at the water inlet side of the water heat exchanger 14, and an outlet pressure sensor 83 provided at the water outlet side of the water heat exchanger 14. The inlet pressure sensor 82 detects the pressure of water at the water inlet of the water heat exchanger 14. The outlet pressure sensor 83 detects the pressure of water at the water outlet of the water heat exchanger 14. The pump suction pressure sensor 81 detects the pressure of water 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 of the present disclosure and the water outlet of the water heat exchanger 14 corresponds to the heat-medium outlet of the water heat exchanger 14 of the present disclosure. Also, the pressure of water corresponds to the heat medium pressure of the present disclosure.

[0023] Also, in the following description, a pressure value detected by the pump suction pressure sensor 81 is defined as P1, a pressure value detected by the inlet pressure sensor 82 is defined as P2, and a pressure value detected by the outlet pressure sensor 83 is defined as P3. Also, the pressure values P1, P2, and P3 detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 each take atmospheric pressure as 0 [kPa] where the value higher than or equal to 0 is at positive pressure and the value less than 0 is at negative pressure.

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

[0025] The controller 7 is connected to various sensors, such as the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83, through a wireless or wired control signal line and detection values from the various sensors are thereby input into the controller 7. Also, the controller 7 is connected to a remote control 6 through a wireless or wired control signal line. The controller 7 is configured to change the operation condition settings in response to the operation of the remote control 6 by a user and display the changed condition settings on the remote control 6. Also, the controller 7 is connected to actuators such as the compressor 11, the air-sending fan 15, the expansion device 13, and the pump 3 through a wireless or wired control signal line. The controller 7 is thereby configured to send operation instructions to the actuators.

[0026] Fig. 2 is a block diagram that illustrates functions of the controller 7 illustrated in Fig. 1. As illustrated in Fig. 2, the controller 7 is provided with, as its functional sections, input circuitry 71, calculation circuitry 72, control circuitry 73, and memory circuitry 74. The input circuitry 71 is a functional section into which detection values from various sensors, such as the pump suction pressure sensor 81, the inlet pressure sensor 82 at the water inlet side of the water heat exchanger 14, and the outlet pressure sensor 83 at the water outlet side of the water heat exchanger 14, are input. Also, the input circuitry 71 receives, from the remote control 6, inputs such as the start and stop of operation and the set temperature at the user side during operation.

[0027] The memory circuitry 74 is a functional section that stores information such as setting information input to the input circuitry 71, various control values used by the control circuitry 73, and determination criteria used by the calculation circuitry 72 for determinations of various abnormalities. Also, during a trial operation immediately after the water-circulating air-conditioning system 100 is assembled, the memory circuitry 74 stores detection values that are input to the input circuitry 71 from the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 such that the detection values are correlated with the operating frequency of the pump 3 at the time.

[0028] The calculation circuitry 72 is a functional section that calculates the control parameters of the actuators on the basis of the information input to the input circuitry 71 and the information stored in the memory circuitry 74. Also, the calculation circuitry 72 determines various abnormalities on the basis of the information input to the input circuitry 71 and the information stored in the memory circuitry 74 and outputs necessary information based on the results of these abnormality determinations to a notification unit 99, which is described later. The details of determinations of various abnormalities are described later.

[0029] As an example of determination of abnormalities, during operation after startup, the calculation circuitry 72 detects and distinguishes between an abnormality around the water heat exchanger 14 and an abnormality around the pump 3 on the basis of the pressure values P1, P2, and P3 detected by the pump suction 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 later) stored in advance in the memory circuitry 74. These pressure values P21, P22, P23, P31, P32, and P33 used during abnormality determinations are described later.

[0030] The control circuitry 73 is a functional section that controls the actuators such as the compressor 11, the air-sending fan 15, the expansion device 13, and the pump 3 on the basis of the control parameters calculated by the calculation circuitry 72. Specifically, the control circuitry 73 controls parameters such as the frequency of the compressor 11, the rotational speed of the air-sending fan 15, the opening degree of the expansion device 13, and the frequency of the pump 3.

[0031] Also, the chiller unit 1 is provided with the notification unit 99, which reports abnormality information in such a case where an abnormality is detected through abnormality determination performed by the calculation circuitry 72. Here, the abnormality information refers, for example, to information such as the results of abnormality determinations that indicate causes in a case where the flow rate calculated from a differential pressure (P2 - P3) across the water heat exchanger 14 is outside the range of the flow rate during operation or countermeasure information that indicates measures to be taken in response to the results of abnormality determinations. Also, the notification unit 99 may also be configured to report abnormality information such as the results of abnormality determinations and countermeasure information in a case where a certain condition is satisfied even when the flow rate calculated from the differential pressure (P2 - P3) across the water heat exchanger 14 is within the range of the flow rate during operation. The notification unit 99 is formed by, for example, a component such as a liquid crystal display and a speaker and reports abnormality information by a means such as text, sound, and light. With such a configuration, for example, a worker engaged in periodic inspection identifies abnormalities in the water flow that arise around the water heat exchanger 14 and around the pump 3 and the locations from which the abnormalities are caused by checking the abnormality information displayed on the notification unit 99.

[0032] Fig. 3 is a diagram that illustrates the relationship between the water head loss [kPa] and the flow rate [m3 / h] at the water heat exchanger 14 illustrated in Fig. 1. Fig. 4 is a diagram that illustrates the relationship between the head [kPa] and the flow rate [m3 / h] at the pump 3 illustrated in Fig. 1. Fig. 5 is a flowchart that illustrates control during a trial operation of the chiller unit 1 illustrated in Fig. 1. The characteristics of the water heat exchanger 14, the characteristics of the pump 3, and the operation of the water-circulating air-conditioning system 100 during a trial operation are described below with reference to Fig. 3 through Fig. 5.

[0033] In the chiller unit 1 of the present disclosure, the controller 7 distinguishes between a plurality of abnormalities that cause changes in the flow rate of water through the water heat exchanger 14 and the pump 3 on the basis of the pressure values P1, P2, and P3 detected by the pump suction 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 that flows through the water heat exchanger 14 and the vertical axis represents the water head loss of water in the water heat exchanger 14. The water head loss is the differential pressure (P2 - P3) across the water heat exchanger 14 and varies depending on factors such as the number of plates included in the water heat exchanger 14, the length of the water flow passage, and the resistance of the water flow passage. In Fig. 4, the horizontal axis represents the flow rate of water that the pump 3 is designed to deliver and the vertical axis represents the head. The head is the amount of pressure increase of water by the pump 3 and is the differential pressure (P2 - P1) across the pump 3. Fig. 4 illustrates pump head curves C1, C2, and C3, which each indicate the relationship between the flow rate of water and the head when the operating frequency of the pump 3 is at a lower operating frequency limit Fp1, an upper operating frequency limit Fp2, and a rated frequency Fp3 (Fp1 <Fp2 <Fp3). Here, the rated frequency Fp3 is, for example, the maximum frequency of the pump 3.

[0035] As illustrated in Fig. 3, when the flow rate of water that flows through the water heat exchanger 14 increases, the flow velocity of water that flows through the water heat exchanger 14 increases and the water head loss of water in the water heat exchanger 14, that is, the differential pressure (P2 - P3) across the water heat exchanger 14, increases. However, for example, when the width of the water flow passage decreases due to a factor such as scale that deposits in the water flow passage of the water heat exchanger 14 and freezing of the water flow passage, there may be a case where the relationship between the water head loss, that is, the differential pressure (P2 - P3), and the flow rate of water deviates from the water head loss line chart illustrated in Fig. 3.

[0036] Also, as illustrated in Fig. 4, at the same operating frequency, as the flow rate of water that the pump 3 delivers increases, the head decreases. At the same flow rate, as the operating frequency of the pump 3 increases, the head increases. Also, at the same head, as the operating frequency of the pump 3 increases, the flow rate increases. However, for example, when the pump 3 is brought into a state where it fails to perform at full capacity due to an abnormality such as air entrainment inside the pump 3, the flow rate of water delivered by the pump 3 decreases, the pressure value P2 at the water discharge side of the pump 3 decreases, and the head, that is, the differential pressure (P2 - P1), decreases. As described above, there may be a case where the relationship between the head, that is, the differential pressure (P2 -P1), and the flow rate deviates from the pump head curves C1 through C3 illustrated in Fig. 4.

[0037] The characteristics of the water heat exchanger 14 illustrated in Fig. 3 (that is, the water head loss line chart) and the characteristics of the pump 3 illustrated in Fig. 4 (that is, the head line chart, which includes the pump head curves C1 through C3 and other elements) are stored in advance in the memory circuitry 74 as initial characteristic data, for example, before the chiller unit 1 is shipped. Note that the characteristics of the pump 3 illustrated in Fig. 4 do not have to be stored in the memory circuitry 74 before shipment. In this case, an operating range of the pump 3 that is compatible with a specified range of the flow rate may also be automatically set during a trial operation by a method described below.

[0038] During Trial Operation of Water-circulating Air-conditioning System 100 As illustrated in Fig. 5, during a trial operation immediately after the water-circulating air-conditioning system 100 is assembled, the operating range of the pump 3 is set, the pressure values P1, P2, and P3 are measured in respective cases where the pump 3 is driven at a plurality of frequencies, and these pressure values are stored in the memory circuitry 74. Immediately after the water-circulating air-conditioning system 100 is assembled, no scale has adhered to or deposited on the water heat exchanger 14, the original water flow passage is maintained, and thus the relationship between the water head loss and the flow rate at the water heat exchanger 14 is the same as the relationship stored in the memory circuitry 74 before shipment of the chiller unit 1 (see Fig. 3). The chiller unit 1 has a program to execute the steps S1 through S5 described below.

[0039] Step S1 First, the chiller unit 1 automatically adjusts the operating frequency of the pump 3 such that the water head loss (that is, P2 - P3) is adjusted to the value indicated for an upper operating flow rate limit V2 in the water head loss line chart (see Fig. 3) of the water heat exchanger 14. Here, for the chiller unit 1, a range of the flow rate of water that flows through the water heat exchanger 14 is defined. Within the defined range of the flow rate, a range of the flow rate is specified according to the site where the chiller unit 1 is installed (specifically, according to a factor such as the load of the site). Consequently, during a trial operation, the pump 3 is driven such that the water head loss (that is, P2 - P3) obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83 is adjusted to a water head loss value L2 (see Fig. 3), which is indicated for the upper limit value of the range of the flow rate at the water heat exchanger 14 specified at the site (that is, the upper operating flow rate limit V2). Subsequently, the operating frequency of the pump 3 at this time is stored in the memory circuitry 74 as the upper operating frequency limit Fp2 (see Fig. 4).

[0040] Step S2 Next, the chiller unit 1 drives the pump 3 at the upper operating frequency limit Fp2 and, at this time, stores, into the memory circuitry 74, the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 such that the pressure values are correlated with the upper operating frequency limit Fp2. In step S2 during the trial operation, the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 are distinguished from the pressure values P1, P2, and P3 detected by these sensors during operation after startup and are referred to as pressure values P11, P12, and P13.

[0041] Step S3 Also, the chiller unit 1 automatically adjusts the operating frequency of the pump 3 such that the water head loss (that is, P2 - P3) is adjusted to the value indicated for a lower operating flow rate limit V1 in the water head loss line chart (see Fig. 3) of the water heat exchanger 14. That is, the pump 3 is driven such that the water head loss obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83 is adjusted to a water head loss value L1 (see Fig. 3), which is indicated for the lower limit value of the range of the flow rate at the water heat exchanger 14 specified at the site (that is, the lower operating flow rate limit V1). Subsequently, the operating frequency of the pump 3 at this time is stored in the memory circuitry 74 as the lower operating frequency limit Fp1 (see Fig. 4).

[0042] Step S4 Next, the chiller unit 1 drives the pump 3 at the lower operating frequency limit Fp1 and, at this time, stores, into the memory circuitry 74, the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 such that the pressure values are correlated with the lower operating frequency limit Fp1. In step S4 during the trial operation, the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 are distinguished from the pressure values P1, P2, and P3 detected by these sensors during operation after startup and are referred to as the pressure values P21, P22, and P23.

[0043] Step S5 Next, the chiller unit 1 drives the pump 3 at a plurality of frequencies between the lower operating frequency limit Fp1 and the upper operating frequency limit Fp2. During operation at each operating frequency, the chiller unit 1 stores the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 into the memory circuitry 74 such that the pressure values are correlated with the operating frequency of the pump 3. In step S5 during the trial operation, the pressure values detected by the pump suction pressure sensor 81, the inlet pressure sensor 82, and the outlet pressure sensor 83 are distinguished from the pressure values P1, P2, and P3 detected by these sensors during operation after startup and are referred to as the pressure values P31, P32, and P33. The pressure values P31, P32, and P33 each vary depending on the operating frequency.

[0044] Note that, in a case where an unillustrated flowmeter is provided to an on-site water piping section 2b (see Fig. 1) included in the water circuit 2 and provided outside the chiller unit 1, the operating frequency of the pump 3 may also be manually adjusted without use of the water head loss line chart of the water heat exchanger 14. Specifically, in step S1, the operating frequency at which the pump 3 is driven such that the value of the flowmeter matches the upper operating flow rate limit V2 is set as the upper operating frequency limit Fp2. Also, in step S3, the operating frequency at which the pump 3 is driven such that the value of the flowmeter matches the lower operating flow rate limit V1 is set as the lower operating frequency limit Fp1.

[0045] As described above, before startup when no scale has deposited on the water heat exchanger 14, a frequency range of the pump 3 that corresponds to the range of the flow rate estimated from the water head loss line chart and the pressure values P2 and P3 detected by the inlet pressure sensor 82 and the outlet pressure sensor 83 is set. Also, before startup when no scale has deposited on the water heat exchanger 14, the pump 3 is driven at a plurality of frequencies and the pressure values, for each frequency, 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. The pressure values P21, P22, P23, P31, P32, and P33 are used as determination criteria to detect and distinguish between an abnormality around the water heat exchanger 14 and an abnormality around the pump 3 during operation after startup.

[0046] During Operation after Startup of Water-circulating Air-conditioning System 100 Fig. 6 is a flowchart that illustrates abnormality determination control of the chiller unit 1 illustrated in Fig. 1. Fig. 7 is an explanatory diagram that illustrates criteria for determination of each abnormality by the controller 7 illustrated in Fig. 1. The abnormality determination control performed by the controller 7 during operation after startup is described below with reference to Fig. 6 and Fig. 7.

[0047] StepS101 As illustrated in Fig. 6, first, it is determined whether the flow rate of water that flows through the water heat exchanger 14 is lower than the lower operating flow rate limit V1 (Step S101). Here, the flow rate of water that flows through the water heat exchanger 14 is obtained, by a procedure such as calculation, from the differential pressure (P2 - P3) across the water heat exchanger 14 obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83, that is, the water head loss, by use of the characteristics (see Fig. 3) stored in the memory circuitry 74.

[0048] In step S101, in a case where it is determined that the flow rate of water that flows through the water heat exchanger 14 is lower than the lower operating flow rate limit V1 (YES in step S101), the determination in step S102 is made. On the other hand, in step S101, in a case where it is determined that the flow rate of water that flows through the water heat exchanger 14 is higher than or equal to the lower operating flow rate limit V1 (NO in step S101), the determination in step S105 is made.

[0049] Step S102 In step S102, it is determined whether the pressure value P1 at the suction side of the pump 3 detected by the pump suction pressure sensor 81 is higher than or equal to 0, that is, whether the pressure value P1 is at positive pressure. In step S102, in a case where it is determined that the pressure value P1 is higher than or equal to 0 (YES in step S102), the determination in step S103 is made. On the other hand, in step S102, in a case where it is determined that the pressure value P1 is lower than 0, that is, the pressure value P1 is at negative pressure (NO in step S102), process A is performed.

[0050] Step S103 In step S103, it is determined whether the pressure value P3 at the water outlet side of the water heat exchanger 14 detected by the outlet pressure sensor 83 is lower than the pressure value P23 obtained during the trial operation (see step S4 in Fig. 5). Here, the pressure value P23 is the detection value detected by the outlet pressure sensor 83 when the pump 3 is driven such that water at the lower operating flow rate limit V1 flows through the water heat exchanger 14 during the trial operation. The pressure value P23 is stored in the memory circuitry 74.

[0051] In step S103, in a case where it is determined that the pressure value P3 is lower than the pressure value P23 obtained during the trial operation (YES in step S103), the determination in step S104 is made. On the other hand, in step S103, in a case where it is determined that the pressure value P3 is higher than or equal to the pressure value P23 obtained during the trial operation (NO in step S103), process B is performed.

[0052] Step S104 In step S104, it is determined whether the pressure value P2 at the inlet side of the water heat exchanger 14 detected by the inlet pressure sensor 82 is higher than the pressure value P22 obtained during the trial operation (see step S4 in Fig. 5). Here, the pressure value P22 is the detection value detected by the inlet pressure sensor 82 when the pump 3 is driven such that water at the lower operating flow rate limit V1 flows through the water heat exchanger 14 during the trial operation. The pressure value P22 is stored in the memory circuitry 74.

[0053] In step S104, in a case where it is determined that the pressure value P2 is higher than the pressure value P22 obtained during the trial operation (YES in step S104), process D is performed and, in a case where it is determined that the pressure value P2 is lower than or equal to the pressure value P22 obtained during the trial operation (NO in step S104), process C is performed.

[0054] Step S105 In step S105, it is determined whether the pressure value P3 is lower than a predetermined lower pressure value limit (for example, half of the pressure value P23 obtained during the trial operation). In a case where the pressure value P3 is lower than the lower pressure value limit (YES in step S105), a state is estimated where almost no water flows through the water heat exchanger 14. Therefore, in this case, it is determined that the water flow is lower than the lower operating flow rate limit V1 regardless of the differential pressure (P2 - P3) across the water heat exchanger 14 and process D is performed. On the other hand, in step S105, in a case where it is determined that the pressure value P3 is higher than or equal to the lower pressure value limit (NO in step S105), the determination in step S106 is made.

[0055] StepS 106 In step S106, it is determined whether the flow rate of water that flows through the water heat exchanger 14 is lower than or equal to the upper operating flow rate limit V2. Here, the flow rate of water that flows through the water heat exchanger 14 is obtained, by a procedure such as calculation, from the differential pressure (P2 -P3) across the water heat exchanger 14 obtained from the inlet pressure sensor 82 and the outlet pressure sensor 83, that is, the water head loss, by use of the characteristics (see Fig. 3) stored in the memory circuitry 74.

[0056] In step S106, in a case where it is determined that the flow rate of water that flows through the water heat exchanger 14 is lower than or equal to the upper operating flow rate limit V2 (YES in step S106), the determination in step S107 is made. On the other hand, in step S106, in a case where it is determined that the flow rate of water that flows through the water heat exchanger 14 exceeds the upper operating flow rate limit V2 (NO in step S106), the procedure returns to step S101.

[0057] StepS 107 In step S107, it is determined whether the pressure value P1 at the suction side of the pump 3 detected by the pump suction pressure sensor 81 is higher than or equal to 0, that is, whether the pressure value P1 is at positive pressure. In step S107, in a case where it is determined that the pressure value P1 is higher than or equal to 0 (YES in step S107), the determination in step S108 is made. On the other hand, in step S107, in a case where it is determined that the pressure value P1 is lower than 0, that is, the pressure value P1 is at negative pressure (NO in step S107), the procedure returns to step S101.

[0058] Step S108 In step S108, it is determined whether the pressure value P3 at 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 trial operation (see step S5 in Fig. 5). Here, the pressure value P33 used as the determination criterion in step S108 is a detected value obtained by the outlet pressure sensor 83 during the trial operation when the pump 3 is driven at the same frequency as the current operating frequency. The pressure value P33 is stored in the memory circuitry 74. Note that the pressure value P33 obtained when the pump 3 is driven at a plurality of operating frequencies during the trial operation may also be stored in the memory circuitry 74 as a function of the operating frequency of the pump 3. In this case, the pressure value P33 used as the determination criterion in step S108 is obtained by calculation from the operating frequency of the pump 3 during the current operation.

[0059] In step S108, in a case where it is determined that the pressure value P3 is lower than the pressure value P33 obtained during the trial operation (YES in step S108), the determination in step S109 is made. On the other hand, in step S108, in a case where it is determined that the pressure value P3 is higher than or equal to the pressure value P33 obtained during the trial operation (NO in step S108), the procedure returns to step S101.

[0060] Step S109 In step S109, it is determined whether the pressure value P2 at 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 trial operation (see step S5 in Fig. 5). Here, the pressure value P32 used as the determination criterion in step S109 is a detected value obtained by the inlet pressure sensor 82 during the trial operation when the pump 3 is driven at the same frequency as the current operating frequency. The pressure value P32 is stored in the memory circuitry 74. Note that the pressure value P32 obtained when the pump 3 is driven at a plurality of operating frequencies during the trial operation may also be stored in the memory circuitry 74 as a function of the operating frequency of the pump 3. In this case, the pressure value P32 used as the determination criterion in step S109 is obtained by calculation from the operating frequency of the pump 3 during the current operation.

[0061] In step S109, in a case where it is determined that the pressure value P2 is higher than the pressure value P32 obtained during the trial operation (YES in step S109), process E is performed. On the other hand, in step S109, in a case where it is determined that the pressure value P2 is lower than or equal to the pressure value P32 obtained during the trial operation (NO in step S109), the procedure returns to step S101.

[0062] Process A through process E are described below with reference to Fig. 6 and Fig. 7. The table in Fig. 7 illustrates, for each of processes A through E, changes, indicated by arrows, in each parameter (a pressure value or a differential pressure) that lead to the respective processes. The changes in each parameter represent the result of a comparison between the parameter values during a trial operation and during an actual operation. An upward arrow indicates that the parameter value is higher during the actual operation than during the trial operation (that is, the parameter value increases) while a downward arrow indicates that the parameter value is lower during the actual operation than during the trial operation (that is, the parameter value decreases).

[0063] Process A As illustrated in Fig. 6 and Fig. 7, process A is performed in a case where, in the abnormality determination control described above, the flow rate obtained from the water head loss (that is, P2 - P3) is lower than the lower operating flow rate limit V1 and the pressure value P1 at the water suction side of the pump 3 is at negative pressure. In process A, since the pressure at the water suction side of the pump 3 is negative, it is determined that the flow rate of water in the water heat exchanger 14 falls below the lower operating flow rate limit V1, and this determination is output to the notification unit 99 as the result of the abnormality determination. Also, together with this result of the abnormality determination, countermeasure information for addressing this abnormality such as "Increase the pressure at the water suction side of the pump" and "Remove an object that causes resistance at the water suction side of the pump" is output to the notification unit 99.

[0064] Also, as illustrated in Fig. 7, when the pressure at the water suction side of the pump 3 is negative, the pressure value P2 at the water inlet side of the water heat exchanger 14 and the pressure value P3 at the water outlet side of the water heat exchanger 14 respectively fall below the pressure value P22 and the pressure value P23 during the trial operation when the water flow is at the lower operating flow rate limit V1.

[0065] Process B As illustrated in Fig. 6 and Fig. 7, process B is performed in a case where, in the abnormality determination control described above, the flow rate obtained from the water head loss (that is, P2 - P3) is lower than the lower operating flow rate limit V1, the pressure value P1 at the water suction side of the pump 3 is at positive pressure, and the pressure value P3 at the water outlet side of the water heat exchanger 14 rises above the pressure value P23 during the trial operation when the water flow is at the lower operating flow rate limit V1. In process B, it is determined that a portion located downstream of the water discharge side of the pump 3 in the water circuit 2 (for example, the on-site water piping section 2b at the water outlet side of the chiller unit 1) is clogged and this determination is output to the notification unit 99 as the result of the abnormality determination.

[0066] Also, as illustrated in Fig. 7, when a portion located downstream of the water discharge side of the pump 3 in the water circuit 2 is clogged, the head (that is, P2 -P1) of the pump 3 rises above the head (P22 - P21) during the trial operation due to the need to compensate for the decrease in the flow rate of the water heat exchanger 14. As a result of the increase in the head, the pressure value P2 at the water inlet side of the water heat exchanger 14 also rises above the pressure value P22 during the trial operation when the water flow is at the lower operating flow rate limit V1.

[0067] Process C As illustrated in Fig. 6 and Fig. 7, process C is performed in a case where, in the abnormality determination control described above, the flow rate obtained from the water head loss (that is, P2 - P3) is lower than the lower operating flow rate limit V1, the pressure value P1 at the water suction side of the pump 3 is at positive pressure, the pressure value P3 at the water outlet side of the water heat exchanger 14 falls below the pressure value P23 during the trial operation when the water flow is at the lower operating flow rate limit V1, and the pressure value P2 at the water inlet side of the water heat exchanger 14 falls below the pressure value P22 during the trial operation when the water flow is at the lower operating flow rate limit V1. In process C, since air is entrained inside the pump 3, it is determined that the flow rate of water in the water heat exchanger 14 falls below the lower operating flow rate limit V1, and this determination is output to the notification unit 99 as the result of the abnormality determination.

[0068] Also, as illustrated in Fig. 7, when air is entrained inside the pump 3, the head (that is, P2 - P1) of the pump 3 falls below the head (P22 - P21) during the trial operation.

[0069] Process D As illustrated in Fig. 6 and Fig. 7, process D is performed in a case where, in the abnormality determination control described above, the flow rate obtained from the water head loss (that is, P2 - P3) is lower than the lower operating flow rate limit V1, the pressure value P1 at the water suction side of the pump 3 is at positive pressure, the pressure value P3 at the water outlet side of the water heat exchanger 14 falls below the pressure value P23 during the trial operation when the water flow is at the lower operating flow rate limit V1, and the pressure value P2 at the water inlet side of the water heat exchanger 14 rises above the pressure value P22 during the trial operation when the water flow is at the lower operating flow rate limit V1. In process D, since the interior of the water heat exchanger 14 freezes, it is determined that the flow rate of water in the water heat exchanger 14 falls below the lower operating flow rate limit V1, and this determination is output to the notification unit 99 as the result of the abnormality determination.

[0070] Also, as illustrated in Fig. 7, when the interior of the water heat exchanger 14 freezes, the differential pressure (P2 - P1) across the pump 3 rises above the head (P22 - P21) during the trial operation.

[0071] Also, in the abnormality determination control illustrated in Fig. 6, process D is performed even in a case where, in step S101, the flow rate obtained from the differential pressure (P2 - P3) across the water heat exchanger 14 is higher than or equal to the lower operating flow rate limit V1, in a case where, in step S105, the pressure value P3 at the water outlet side of the water heat exchanger 14 is lower than the lower pressure value limit (half of the pressure value P23 obtained during the trial operation when the water flow is at the lower operating flow rate limit V1). This is because even in a case where the flow rate obtained from the differential pressure (P2 - P3) across the water heat exchanger 14 is higher than or equal to the lower operating flow rate limit V1, there may also be a case where, in actuality, freezing of the interior of the water heat exchanger 14 narrows the water flow passage and, as a result, the flow rate is lower than the lower operating flow rate limit V1. In this case, since the pressure value P3 is lower than the lower pressure value limit, as illustrated in Fig. 7, the differential pressure (P2 - P3) across the water heat exchanger 14 rises above the water head loss (P22 - P23) during the trial operation when the water flow is at the lower operating flow rate limit V1.

[0072] Process E As illustrated in Fig. 6 and Fig. 7, process E is performed in a case where, in the abnormality determination control described above, the flow rate obtained from the water head loss (that is, P2 - P3) is higher than or equal to the lower operating flow rate limit V1 and lower than or equal to the upper operating flow rate limit V2, the pressure value P1 at the water suction side of the pump 3 is at positive pressure, the pressure value P3 at the water outlet side of the water heat exchanger 14 falls below the pressure value P33 during the trial operation at the same operating frequency, and the pressure value P2 at the water inlet side of the water heat exchanger 14 rises above the pressure value P32 during the trial operation at the same operating frequency. In other words, process E is performed in a case where, although the flow rate obtained from the water head loss (that is, P2 - P3) is within the specified range of the flow rate, the pressure value P2 at the water inlet side of the water heat exchanger 14 rises above the pressure value P32 and the pressure value P3 at the water outlet side of the water heat exchanger 14 falls below the pressure value P33, with the pressure value P32 and the pressure value P33 obtained during the trial operation when the pump 3 is driven at the same frequency as the current operating frequency. In process E, it is determined that scale or other debris forms in the water flow passage of the water heat exchanger 14 and this determination is output to the notification unit 99 as the result of the abnormality determination. Also, together with this result of the abnormality determination, countermeasure information for addressing this abnormality such as "Clean the water heat exchanger" is output to the notification unit 99. Note that, to more accurately distinguish between the case where the interior of the water heat exchanger 14 freezes (the case where process D is performed) and the case where scale forms in the water flow passage of the water heat exchanger 14 (the case where process E is performed), process D and process E may also further be distinguished depending on a factor such as the temperature of water in the water flow passage of the water heat exchanger 14 and the operating accumulation time. In this case, the water heat exchanger 14 is provided with a temperature sensor that detects the temperature of water in the water flow passage of the water heat exchanger 14.

[0073] Also, as illustrated in Fig. 7, when debris forms in the water flow passage of the water heat exchanger 14, the differential pressure (P2 - P3) across the water heat exchanger 14 rises above the water head loss (P32 - P33) during the trial operation at the same operating frequency. Also, the differential pressure (P2 - P1) across the pump 3 rises above the head (P32 - P31) during the trial operation.

[0074] Among processes A through E described above, in processes A through D in which the flow rate is outside the prespecified range of the flow rate, control such as stopping the operation may also be performed. On the other hand, in process E, the operation may also be continued because the flow rate is within the prespecified range of the flow rate, although the abnormality information is output to the notification unit 99. In both the case where the interior of the water heat exchanger 14 freezes (the case where process D is performed) and the case where scale forms in the water flow passage of the water heat exchanger 14 (the case where process E is performed), the respective transitions of the pressure values P2 and P3 are similar and the progress of freezing of the interior is relatively fast compared to the increase of scale. As a result, the flow rate falls below the lower operating flow rate limit V1 in a shorter time in a case where the interior freezes than in a case where scale forms. The water flow rapidly decreases and, for example, the pressure value P3 falls below the lower pressure value limit (half of the pressure value P23 obtained during the trial operation).

[0075] In the embodiment described above, the chiller unit 1 is described by taking as an example the case where the water heat exchanger 14 serves as an evaporator in the refrigerant circuit 10 and water is cooled to a target temperature by the heat of heat source-side refrigerant such as a fluorocarbon. However, the chiller unit 1 may also be provided with a four-way valve in the refrigerant circuit 10 and be configured not only to cool water to a target temperature but also to heat water to a target temperature, by the heat of heat source-side refrigerant such as a fluorocarbon. Also, Fig. 1 illustrates a structure in which refrigerant in the refrigerant flow passage and water in the water flow passage of the water heat exchanger 14 flow in opposite directions; however, a structure may also be applied in which the refrigerant and the water flow in parallel directions.

[0076] Also, although a heat medium that flows through the water circuit 2 is described as water, by changing the information on the physical properties of the heat medium, not only water but also brine may be used as the heat medium. For example, when the controller 7 is configured to calculate the water head loss line chart of the water heat exchanger 14 from the type and concentration of brine, even in a case where the brine is used, the same operation is performed as in a case where water is used.

[0077] As described above, the chiller unit 1 is provided with the heat-medium piping section (the water piping section 2a), which forms a portion of the heat-medium circuit (the water circuit 2) and through which a heat medium flows; the refrigerant circuit 10, which has the compressor 11 configured to compress refrigerant and through which the refrigerant circulates by the compressor 11; and the heat-medium heat exchanger (the water heat exchanger 14), which allows the heat medium and the refrigerant to exchange heat with each other. The heat-medium heat exchanger (the water heat exchanger 14) has the heat-medium passage through which a heat medium flows and the refrigerant flow passage through which refrigerant flows, is provided in the heat-medium piping section (the water piping section 2a), and forms a portion of the heat-medium circuit and a portion of the refrigerant circuit 10. Also, the chiller unit 1 is provided with the pump 3, which is provided upstream of the heat-medium heat exchanger of the heat-medium piping section and configured to deliver a heat medium to the heat-medium heat exchanger, and the pump suction pressure sensor 81 configured to detect the heat medium pressure at the suction side of the pump 3. Also, the chiller unit 1 is provided with the inlet pressure sensor 82 configured to detect the heat medium pressure at the discharge side of the pump 3 and at the heatmedium inlet side of the heat-medium heat exchanger (the water heat exchanger 14) and the outlet pressure sensor 83 configured to detect the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger.

[0078] As described above, the chiller unit 1 is provided with the water pressure sensors at respective positions, which are one at the suction side of the pump, another at the heat-medium inlet side of the heat-medium heat exchanger, and the other at the heat-medium outlet side of the heat-medium heat exchanger and is thereby configured to detect and distinguish between an abnormality around the heatmedium heat exchanger and an abnormality around the pump. In addition, when the notification unit 99 or a similar unit is provided that reports abnormality information, a worker engaged in periodic inspection only needs to treat or check the necessary portion with reference to the reported abnormality information. The range of the portion to be treated or checked is narrower and the working hours are shorter than in the case of some chiller unit.

[0079] Also, the chiller unit 1 is provided with the controller 7 configured to detect an abnormality in the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) on the basis of the heat medium pressure (the pressure value P1) at the suction side of the pump 3 detected by the pump suction pressure sensor 81, the heat medium pressure (the pressure value P2) at the heat-medium inlet side of the heat-medium heat exchanger detected by the inlet pressure sensor 82, and the heat medium pressure (the pressure value P3) at the heat-medium outlet side of the heat-medium heat exchanger detected by the outlet pressure sensor 83.

[0080] Also, the controller 7, in a case where a flow rate of the heat medium that is calculated from the differential pressure (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 falls below the lower operating flow rate limit V1, which is predetermined, determines that the cause lies upstream of the pump 3 in a case where the heat medium pressure (the pressure value P1) at the suction side of the pump 3 is negative pressure.

[0081] Consequently, in a case where the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) falls below the lower operating flow rate limit V1, it is possible to determine, in the water circuit 2, not only a case where the cause lies inside the water heat exchanger 14 or the pump 3 but also a case where the cause lies upstream of the pump 3.

[0082] Also, the controller 7 stores the heat medium pressure (the pressure value P21) at the suction side of the pump 3, the heat medium pressure (the pressure value P22) at the heat-medium inlet side of the heat-medium heat exchanger, and the heat medium pressure (the pressure value P23) at the heat-medium outlet side of the heat-medium heat exchanger, with each heat medium pressure detected when the pump 3 is driven at the lower operating frequency limit Fp1, which is predetermined, during a trial operation before startup. Subsequently, the controller 7, during operation after startup, in a case where a flow rate of the heat medium that is calculated on the basis of the differential pressure (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 and the heat medium pressure (the pressure value P3) at the heatmedium outlet side of the heat-medium heat exchanger falls below the lower operating flow rate limit V1, which is predetermined, determines the cause by which the flow rate of the heat medium falls below the lower operating flow rate limit V1 by comparing the heat medium pressure (the pressure value P1) at the suction side of the pump 3 during operation with the heat medium pressure (the pressure value P21) at the suction side of the pump 3 detected when the pump 3 is driven at the lower operating frequency limit Fp1 during the trial operation, by comparing the heat medium pressure (the pressure value P2) at the heat-medium inlet side of the heatmedium heat exchanger during operation with the heat medium pressure (the pressure value P22) at the heat-medium inlet side of the heat-medium heat exchanger during the trial operation, and by comparing the heat medium pressure (the pressure value P3) at the heat-medium outlet side of the heat-medium heat exchanger during operation with the heat medium pressure (the pressure value P23) at the heat-medium outlet side of the heat-medium heat exchanger during the trial operation, that is, 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.

[0083] Compared with some configuration, adding the pump suction pressure sensor 81 enables the heat medium pressure (the pressure values P1 and P21) at the suction side of the pump 3 to be detected by the pump suction pressure sensor 81 and also the differential pressure (P2 - P1) across the pump 3, that is, the head, to be calculated. The number of parameters used for abnormality determination thus increases and causes are therefore distinguished in more detail.

[0084] The controller 7, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit V1, determines that a cause by which the flow rate of the heat medium falls below the lower operating flow rate limit V1 lies downstream of the heat-medium heat exchanger in a case where the heat medium pressure (the pressure value P1) at the suction side of the pump 3 is positive pressure and the heat medium pressure (the pressure value P3) at the heatmedium outlet side of the heat-medium heat exchanger rises above the heat medium pressure (P23) at the heat-medium outlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit Fp1 during the trial operation.

[0085] Consequently, in a case where the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) falls below the lower operating flow rate limit V1, it is possible to determine, in the water circuit 2, not only a case where the cause lies inside the water heat exchanger 14 or the pump 3 but also a case where the cause lies downstream of the water heat exchanger 14.

[0086] Also, the controller 7, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit V1, determines that a cause by which the flow rate of the heat medium falls below the lower operating flow rate limit lies inside the pump 3 in a case where the heat medium pressure (the pressure value P1) at the suction side of the pump 3 is positive pressure and the heat medium pressure (the pressure value P2) at the heat-medium inlet side of the heatmedium heat exchanger falls below the heat medium pressure (the pressure value P22) at the heat-medium inlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit Fp1 during the trial operation.

[0087] Consequently, in a case where the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) falls below the lower operating flow rate limit V1, it is possible to detect and distinguish between a case where the cause lies in the heat-medium heat exchanger and a case where the cause lies upstream of the heat-medium heat exchanger, such as air entrained inside the pump 3.

[0088] The controller 7, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit V1, determines that the flow rate of the heat medium falls below the lower operating flow rate limit V1 because the interior of the heat-medium heat exchanger freezes in a case where the heat medium pressure (the pressure value P1) at the suction side of the pump 3 is positive pressure and the heat medium pressure (the pressure value P2) at the heatmedium inlet side of the heat-medium heat exchanger rises above the heat medium pressure (the pressure value P22) at the heat-medium inlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit Fp1 during the trial operation.

[0089] Consequently, in a case where the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) falls below the lower operating flow rate limit V1, it is possible to distinguish the cause due to freezing inside the heat-medium heat exchanger from a case where the cause lies at the pump 3. Here, the result of abnormality determination may also be fed back to control of a component such as the compressor 11. For example, in a case where the cause by which the flow rate of a heat medium in the heat-medium heat exchanger falls is determined to be freezing inside the heat-medium heat exchanger, the operating frequency of the compressor 11 is preferably adjusted such that the temperature of the water heat exchanger 14 rises.

[0090] Also, the controller 7 stores the heat medium pressure (the pressure value P31) at the suction side of the pump 3, the heat medium pressure (the pressure value P32) at the heat-medium inlet side of the heat-medium heat exchanger, and the heat medium pressure (the pressure value P33) at the heat-medium outlet side of the heat-medium heat exchanger, with each heat medium pressure detected in each case where the pump 3 is driven at one of a plurality of frequencies during a trial operation before startup. Subsequently, the controller 7, during operation after startup, in a case where a flow rate of the heat medium that is calculated on the basis of the differential pressure (P2 - P3) between the heat medium pressure (the pressure value P2) at the heat-medium inlet side of the heat-medium heat exchanger and the heat medium pressure (the pressure value P3) at the heat-medium outlet side of the heat-medium heat exchanger and the heat medium pressure (the pressure value P3) at the heat-medium outlet side of the heat-medium heat exchanger stays within the range of the flow rate during operation, which is predetermined, determines that debris forms inside the heat-medium heat exchanger in a case where the heat medium pressure (the pressure value P1) at the suction side of the pump 3 is positive pressure, the heat medium pressure (the pressure value P2) at the heat-medium inlet side of the heat-medium heat exchanger rises above the heat medium pressure (the pressure value P32) at the heat-medium inlet side of the heat-medium heat exchanger during a trial operation in which the pump is driven at the same frequency as during operation, and the heat medium pressure (the pressure value P3) at the heat-medium outlet side of the heat-medium heat exchanger falls below the heat medium pressure (the pressure value P33) at the heat-medium outlet side of the heat-medium heat exchanger during the trial operation in which the pump is driven at the same frequency as during operation.

[0091] This configuration makes it possible to detect a case where the flow rate of the heat medium in the heat-medium heat exchanger (the water heat exchanger 14) falls below the flow rate during the trial operation due to scale formation, even when the flow rate does not fall below the lower operating flow rate limit V1. Incidentally, when scale deposits in the water flow passage of the water heat exchanger 14, there may be a case where the scale hinders heat exchange between water and refrigerant and the coefficient of performance (COP) of the chiller unit 1 thus decreases. For this reason, the configuration is preferably made such that a notification of scale in the water heat exchanger 14 is issued before the flow rate falls below the lower operating flow rate limit V1 due to the scale. Also, during operation, a state where the water flow passage is preferably secured, that is, a state of good heat exchange efficiency is preferably maintained, through cleaning or other treatment.

[0092] Also, the chiller unit 1 is provided with the notification unit 99, which reports abnormality information on the abnormality in a case where the abnormality in the flow rate of a heat medium that flows through the heat-medium heat exchanger (the water heat exchanger 14) is detected by the controller 7. With this configuration, for example, a worker engaged in periodic inspection identifies abnormalities in the water flow that arise around the water heat exchanger 14 and around the pump 3 and abnormality information on the abnormalities (for example, the locations from which the abnormalities are caused) by checking the abnormality information reported by the notification unit 99. Reference Signs List

[0093] 1: chiller 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: controller, 10: refrigerant circuit, 11: compressor, 12: heat source-side heat exchanger, 13: expansion device, 14: water heat exchanger, 15: air-sending fan, 71: input circuitry, 72: calculation circuitry, 73: control circuitry, 74: memory circuitry, 81: pump suction pressure sensor, 82: inlet pressure sensor, 83: outlet pressure sensor, 99: notification unit, 100: water-circulating air-conditioning system, A, B, C, D, E: process, C1, C2, C3: pump head curve, Fp1: lower operating frequency limit, Fp2: upper operating frequency limit, Fp3: rated frequency, L1: water head loss value, L2: water head loss value, P1, P11, P12, P13, P2, P21, P22, P23, P3, P31, P32, P33: pressure value, V1: lower operating flow rate limit, V2: upper operating flow rate limit

Claims

1. A chiller unit comprising:a heat-medium piping section that forms a portion of a heat-medium circuit and through which a heat medium flows;a refrigerant circuit that has a compressor configured to compress refrigerant and through which the refrigerant circulates by the compressor;a heat-medium heat exchanger that has a heat-medium passage through which the heat medium flows and a refrigerant flow passage through which the refrigerant flows, is provided at the heat-medium piping section, and forms a portion of the heat-medium circuit and a portion of the refrigerant circuit, the heat-medium heat exchanger allowing the heat medium and the refrigerant to exchange heat with each other;a pump provided upstream of the heat-medium heat exchanger of the heatmedium piping section and configured to deliver the heat medium to the heat-medium heat exchanger;a pump suction pressure sensor configured to detect heat medium pressure at a suction side of the pump;an inlet pressure sensor configured to detect heat medium pressure at a discharge side of the pump and at a heat-medium inlet side of the heat-medium heat exchanger; andan outlet pressure sensor configured to detect heat medium pressure at a heatmedium outlet side of the heat-medium heat exchanger.

2. The chiller unit of claim 1, further comprising a controller configured to detect an abnormality in a flow rate of the heat medium that flows through the heat-medium heat exchanger on the basis of the heat medium pressure at the suction side of the pump detected by the pump suction 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 theheat-medium heat exchanger detected by the outlet pressure sensor.

3. The chiller unit of claim 2, wherein the controller is configured to, in a case where a flow rate of the heat medium that is calculated from a 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 falls below a lower operating flow rate limit, which is predetermined, determine that a cause lies upstream of the pump in a case where the heat medium pressure at the suction side of the pump is negative pressure.

4. The chiller unit of claim 2 or 3, whereinthe controller is configured to store the heat medium pressure at 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, each heat medium pressure being detected when the pump is driven at a lower operating frequency limit, which is predetermined, during a trial operation before startup, andthe controller is configured to, during operation after startup, in a case where a flow rate of the heat medium that is calculated on the basis of a 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 heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger falls below a lower operating flow rate limit, which is predetermined, determine a cause by which the flow rate of the heat medium falls below the lower operating flow rate limit by comparing the heat medium pressure at the suction side of the pump during operation with the heat medium pressure at the suction side of the pump detected when the pump is driven at the lower operating frequency limit during the trial operation, by comparing the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger during operation with the heat medium pressure at the heat-medium inlet side of theheat-medium heat exchanger during the trial operation, and by comparing the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger during operation with the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger during the trial operation.

5. The chiller unit of claim 4, wherein the controller is configured to, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit, determine that a cause by which the flow rate of the heat medium falls below the lower operating flow rate limit lies downstream of the heat-medium heat exchanger in a case where the heat medium pressure at the suction side of the pump is positive pressure and the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger rises above the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit during the trial operation.

6. The chiller unit of claim 4 or 5, wherein the controller is configured to, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit, determine that a cause by which the flow rate of the heat medium falls below the lower operating flow rate limit lies inside the pump in a case where the heat medium pressure at the suction side of the pump is positive pressure and the heat medium pressure at the heat-medium inlet side of the heatmedium heat exchanger falls below the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit during the trial operation.

7. The chiller unit of any one of claims 4 to 6, wherein the controller is configured to, during operation, in a case where the calculated flow rate of the heat medium falls below the lower operating flow rate limit, determine that the flow rate of the heat medium falls below the lower operating flow rate limit because an interior of the heatmedium heat exchanger freezes in a case where the heat medium pressure at the suction side of the pump is positive pressure and the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger rises above the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger when the pump is driven at the lower operating frequency limit during the trial operation.

8. The chiller unit of any one of claims 2 to 7, whereinthe controller is configured to store the heat medium pressure at 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, each heat medium pressure being detected in each case where the pump is driven at one of a plurality of frequencies during a trial operation before startup, andthe controller is configured to, during operation after startup, in a case where a flow rate of the heat medium that is calculated on the basis of a 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 heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger stays within a range of the flow rate during operation, which is predetermined, determine that debris forms inside the heatmedium heat exchanger in a case where the heat medium pressure at the suction side of the pump is positive pressure, the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger rises above the heat medium pressure at the heat-medium inlet side of the heat-medium heat exchanger during the trial operation in which the pump is driven at the same frequency as during operation, and the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger falls below the heat medium pressure at the heat-medium outlet side of the heat-medium heat exchanger during the trial operation in which the pump is driven at the same frequency as during operation.

9. The chiller unit of any one of claims 2 to 8, further comprising a notification unit configured to report abnormality information on the abnormality in a case where the abnormality in the flow rate of the heat medium that flows through the heat-medium5 heat exchanger is detected by the controller.

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