Refrigeration Cycle System

Abstract

The refrigeration cycle system comprises: a refrigerant circuit which has a compressor and through which a refrigerant is circulated by the compressor; a heat medium circuit which has a heat source side pump and through which a heat medium is circulated by the heat source side pump; a heat exchanger that exchanges heat between the refrigerant and the heat medium; and a system control device that controls the heat source side pump. The heat medium circuit has a load device provided on the downstream side of the heat exchanger, and a bypass piping that bypasses the load device. The refrigeration cycle system comprises a first detection unit that is provided to the heat medium circuit and that detects pressure difference before and after the heat exchanger, and a second detection unit that is provided to the heat medium circuit and that detects bypass pressure difference before and after the bypass piping. The system control device obtains the lift of the heat source side pump from the pressure difference detected by the first detection unit and the rotational speed of the heat source side pump, calculates the bypass pressure difference before and after the bypass piping on the basis of the pressure difference and the lift, and determines the deposition state of scales in the heat exchanger by comparing, with a pre-stored difference value, the difference between a calculation value of the calculated bypass pressure difference and an actual measurement of the bypass pressure difference detected by the second detection unit.

Description

[Technical field]

[0001] The present disclosure relates to a refrigeration cycle system that supplies a heat medium, such as water, that has exchanged heat with a refrigerant to a load device. [Background technology]

[0002] Some refrigeration cycle systems include a refrigeration cycle device, which is a heat source machine equipped with a refrigerant circuit through which a refrigerant circulates, and the refrigeration cycle device exchanges heat between a heat medium (e.g., water) in a heat medium circuit and the refrigerant, and supplies the heat medium after the heat exchange to a load device (e.g., an air conditioner). In the refrigeration cycle system, the heat exchange efficiency of a heat exchanger (hereinafter also referred to as a water heat exchanger) in which a refrigerant and a heat medium exchange heat with each other decreases as scale accumulates in the flow path of the heat medium over time due to calcium components and the like contained in the heat medium. When the amount of dirt such as scale in the water heat exchanger exceeds a certain amount, the heat exchange between the refrigerant and the heat medium may be extremely hindered, leading to an abnormal state. In some refrigeration cycle systems, the accumulation state of dirt can be diagnosed, and a worker performing regular inspections cleans the water heat exchanger according to the diagnosis result, thereby preventing the occurrence of clogging of the water heat exchanger, i.e., an abnormal state (see, for example, Patent Document 1). The refrigeration cycle system of Patent Document 1 diagnoses the accumulation state of dirt based on the heat exchange efficiency between the refrigerant and the heat medium. Specifically, the refrigeration cycle system of Patent Document 1 calculates the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the water heat exchanger, and uses this temperature difference to diagnose the state of dirt accumulation in the water heat exchanger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 250789 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since a refrigerant generally repeats a refrigeration cycle accompanied by changes in state, pressure, and temperature while circulating through a refrigerant circuit, the saturation temperature of the refrigerant is likely to change due to changes in load and operating conditions. Therefore, in a configuration in which the accumulation state of dirt in the water heat exchanger is determined using the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the water heat exchanger as in Patent Document 1, there is a problem with the accuracy of the determination due to the influence of changes in load and operating conditions.

[0005] The present disclosure has been made against the background of the above-mentioned problems, and provides a refrigeration cycle system that can determine the state of dirt accumulation in the heat medium flow path of a water heat exchanger (heat exchanger) more accurately than conventional methods. [Means for solving the problem]

[0006] A first refrigeration cycle system according to the present disclosure includes a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor, a heat medium circuit having a heat source side pump and in which a heat medium is circulated by the heat source side pump, a heat exchanger that performs heat exchange between the refrigerant and the heat medium, and a system control device that controls the heat source side pump, wherein the heat medium circuit includes a load device provided downstream of the heat exchanger and a bypass piping that bypasses the load device. In the refrigeration cycle system, a first detector is provided in the heat medium circuit and detects a differential pressure between before and after the heat exchanger. and a second detection unit provided in the heat medium circuit and configured to detect a bypass differential pressure before and after the bypass piping, wherein the system control device determines a head of the heat source side pump from the differential pressure detected by the first detection unit and a rotation speed of the heat source side pump, calculates the bypass differential pressure before and after the bypass piping based on the differential pressure and the head, and determines a scale deposition state of the heat exchanger by comparing a difference between the calculated bypass differential pressure value and an actual measured value of the bypass differential pressure detected by the second detection unit with a pre-stored difference value.

[0007] A second refrigeration cycle system according to the present disclosure includes a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor, a heat medium circuit having a heat source side pump and in which a heat medium is circulated by the heat source side pump, a heat exchanger that performs heat exchange between the refrigerant and the heat medium, and a system control device that controls the heat source side pump, wherein the heat medium circuit includes a load device provided downstream of the heat exchanger and a bypass piping that bypasses the load device. In this refrigeration cycle system, the refrigeration cycle system further includes a first detection unit that is provided in the heat medium circuit and detects a differential pressure between before and after the heat exchanger, and a pump control unit that is provided in the heat medium circuit and detects a differential pressure between before and after the heat source side pump. and a second detection unit that detects a differential pressure, and the system control device determines the head of the heat source side pump from the differential pressure detected by the first detection unit and the rotation speed of the heat source side pump, calculates a bypass differential pressure before and after the bypass piping based on the differential pressure and the head to obtain a first calculated value, and calculates the bypass differential pressure before and after the bypass piping based on the differential pressure detected by the first detection unit and the pump differential pressure detected by the second detection unit to obtain a second calculated value, and determines a scale deposition state of the heat exchanger by comparing a difference between the first calculated value and the second calculated value of the bypass differential pressure with a pre-stored difference value.

[0008] A third refrigeration cycle system according to the present disclosure includes a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor, a heat medium circuit having a heat source side pump and a load side pump and in which a heat medium is circulated by the heat source side pump and the load side pump, a heat exchanger that performs heat exchange between the refrigerant and the heat medium, and a system control device that controls the heat source side pump, wherein the heat medium circuit includes a load device provided downstream of the heat exchanger and a free bypass piping that bypasses the load device, the heat source side pump pressure-feeds the heat medium to the heat exchanger, and the load side pump pressure-feeds the heat medium to the load device. The system control device determines a load side flow rate of the heat medium flowing on the load side of the heat medium circuit based on the differential pressure detected by the first detection unit and the rotation speed of the heat source side pump, calculates the load side flow rate of the heat medium flowing on the load side of the heat medium circuit based on the differential pressure and the head, and determines a scale accumulation state of the heat exchanger by comparing a difference between the calculated load side flow rate and an actual value of the load side flow rate detected by the second detection unit with a pre-stored difference value.

[0009] A fourth refrigeration cycle system according to the present disclosure includes a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor, a heat medium circuit having a heat source side pump and a load side pump and in which a heat medium is circulated by the heat source side pump and the load side pump, a heat exchanger that exchanges heat between the refrigerant and the heat medium, and a system control device that controls the heat source side pump, wherein the heat medium circuit has a load device provided downstream of the heat exchanger and a free bypass piping that bypasses the load device, the heat source side pump pressure-feeds the heat medium to the heat exchanger, and the load side pump pressure-feeds the heat medium to the load device. In this refrigeration cycle system, and a second detection unit provided in the heat medium circuit and detecting a pump pressure difference between before and after the heat source side pump, wherein the system control device determines a head of the heat source side pump from the pressure difference detected by the first detection unit and a rotation speed of the heat source side pump, calculates a load side flow rate of the heat medium flowing on the load side of the heat medium circuit based on the pressure difference detected by the first detection unit and the head to obtain a first calculated value, calculates the load side flow rate of the heat medium flowing on the load side of the heat medium circuit based on the pressure difference detected by the first detection unit and the pump pressure difference detected by the second detection unit to obtain a second calculated value, and determines a scale accumulation state of the heat exchanger by comparing a difference between the first calculated value and the second calculated value of the load side flow rate with a pre-stored difference value. Effect of the Invention

[0010] In the first, second, third and fourth refrigeration cycle systems according to the present disclosure, the difference between the calculated and actual values ​​of the bypass differential pressure (or load side flow rate) obtained by different methods using a first and second detection unit provided in the heat medium circuit, or the difference between the first and second calculated values ​​of the bypass differential pressure (or load side flow rate), is compared with a pre-stored difference value to determine the scale buildup state of the heat exchanger. In the present disclosure, the first and second detection units are both provided in the heat medium circuit where scale buildup occurs, and therefore, by determining the scale buildup state of the heat exchanger based on the detection values, the scale buildup state of the heat exchanger can be determined more accurately with less influence from load fluctuations and fluctuations in operating conditions, compared to a conventional configuration in which the scale buildup state of the heat exchanger is determined based on the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the heat exchanger. [Brief description of the drawings]

[0011] [Figure 1] 1 is a circuit diagram showing a schematic configuration of a refrigeration cycle system according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a circuit diagram showing an example of the configuration of the refrigeration cycle device of FIG. [Diagram 3] FIG. 2 is a diagram showing the relationship between head loss and flow rate of the water heat exchanger of FIG. [Figure 4] FIG. 2 is a diagram showing the head characteristics of the pump in FIG. [Diagram 5] 2 is a flowchart showing a scale accumulation determination process performed by the system control device of FIG. 1. [Figure 6] FIG. 3 is a circuit diagram showing a modified example of the refrigeration cycle device of FIG. [Figure 7] FIG. 6 is a circuit diagram showing a schematic configuration of a refrigeration cycle system according to a second embodiment of the present disclosure. [Figure 8] 8 is a flowchart showing a scale accumulation determination process performed by the system control device of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the refrigeration cycle system according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiment, and various modifications can be made without departing from the spirit of the present disclosure. The refrigeration cycle system shown in the drawings is an example of the refrigeration cycle system of the present disclosure, and the refrigeration cycle system of the present disclosure is not limited to the refrigeration cycle system shown in the drawings. In addition, in each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the entire specification.

[0013] Embodiment 1 (Configuration of refrigeration cycle system 10) Fig. 1 is a circuit diagram showing a schematic configuration of a refrigeration cycle system 10 according to a first embodiment of the present disclosure. Fig. 2 is a circuit diagram showing an example of the configuration of a refrigeration cycle device 20 of Fig. 1. In Fig. 2, solid white arrows indicate the flow direction of a refrigerant, and in Figs. 1 and 2, dashed white arrows indicate the flow direction of a heat medium. The schematic configuration of the refrigeration cycle system 10 will be described with reference to Figs. 1 and 2.

[0014] 1, the refrigeration cycle system 10 includes a refrigerant circuit 27 through which a refrigerant circulates, a heat medium circuit 40 through which a heat medium such as water circulates, and a water heat exchanger (hereinafter also referred to as a heat exchanger 26) that exchanges heat between the refrigerant and the heat medium. Note that the heat medium flowing through the heat medium circuit 40 is water, but other fluids such as antifreeze may also be used. The heat medium circuit 40 includes a heat source side pump 30 that pumps the heat medium to the heat exchanger 26, and supplies the heat medium that has exchanged heat with the refrigerant in the heat exchanger 26 to a load device 70. The load device 70 is, for example, an air conditioner.

[0015] The refrigeration cycle system 10 of FIG. 1 includes a plurality of refrigeration cycle devices 20 each having a refrigerant circuit 27. The number of refrigeration cycle devices 20 included in the refrigeration cycle system 10 may be any number, for example, it may be one. The refrigeration cycle device 20 functions as a heat source device, for example, an air-cooled heat pump chiller. The refrigeration cycle device 20 includes a part of a heat medium circuit 40. Each of the plurality of refrigeration cycle devices 20 has a heat source side branch pipe 40a described later in which a water heat exchanger (heat exchanger 26) and a heat source side pump 30 are provided. In the heat medium circuit 40, the plurality of heat source side branch pipes 40a are connected in parallel to each other and connected to a circuit portion on the load side. That is, the refrigeration cycle system 10 is configured to exchange heat between a heat medium circulating in one heat medium circuit 40 and a refrigerant circulating in each refrigerant circuit 27 of the plurality of refrigeration cycle devices 20, and the heat generated in the plurality of refrigeration cycle devices 20 is supplied to one or more load devices 70 via the heat medium. The configuration of the heat medium circuit 40 will be described later.

[0016] As shown in FIG. 2, the refrigerant circuit 27 is formed by connecting the compressor 22, the air heat exchanger (heat exchanger 24), the pressure reducing device 25, and the water heat exchanger (heat exchanger 26) in a ring shape via refrigerant piping. The compressor 22 compresses the refrigerant and circulates it in the refrigerant circuit 27. The compressor 22 is, for example, an inverter compressor whose capacity, which is the amount of refrigerant sent out per unit time, is controlled by changing the operating frequency. The heat exchanger 24 is, for example, a fin-and-tube type heat exchanger, and exchanges heat between the air and the refrigerant. The fan 28 supplies outdoor air to the heat exchanger 24 to promote heat exchange by the heat exchanger 24. The amount of air sent to the heat exchanger 24 is controlled by controlling the rotation speed of the fan 28. The pressure reducing device 25 is, for example, an electronic expansion valve, and controls the pressure of the refrigerant flowing into the water heat exchanger (heat exchanger 26) by changing the opening degree. The pressure reducing device 25 reduces the pressure of the high-pressure refrigerant flowing out of the heat exchanger 24. The heat exchanger 26 exchanges heat between the heat medium circulating in the heat medium circuit 40 and the refrigerant flowing in the refrigerant circuit 27.

[0017] In the refrigerant circuit 27 of FIG. 2, the discharge side of the compressor 22 is connected to an air heat exchanger (heat exchanger 24), the heat exchanger 24 is connected to a pressure reducing device 25, the pressure reducing device 25 is connected to a water heat exchanger (heat exchanger 26), and the heat exchanger 26 is connected to the suction side of the compressor 22. In this case, the heat exchanger 24 functions as a condenser, and the water heat exchanger (heat exchanger 26) functions as an evaporator. In the heat exchanger 26, the heat medium pumped by the heat source side pump 30 is cooled by the refrigerant decompressed by the pressure reducing device 25 of the refrigerant circuit 27. In the example of FIG. 2, the heat medium and the refrigerant flow in parallel in the heat exchanger 26.

[0018] The configuration of the refrigerant circuit 27 is not limited to this configuration. For example, a flow path switching device such as a four-way valve may be provided on the refrigerant discharge side of the compressor 22 to switch between a cooling operation in which the refrigerant flows through the compressor 22, the heat exchanger 24, the pressure reducing device 25, and the heat exchanger 26 in this order, and a heating operation in which the refrigerant flows through the compressor 22, the heat exchanger 26, the pressure reducing device 25, and the heat exchanger 24 in this order. In the example of Fig. 2, the heat exchanger 24, which is a condenser, is configured as an air heat exchanger, and the refrigeration cycle device 20 is an air-cooled type, but the heat exchanger 24 may be configured as a water heat exchanger, and the refrigeration cycle device 20 may be a water-cooled type.

[0019] The refrigeration cycle device 20 also includes a control device 21 that controls the refrigerant circuit 27 and the heat source side pump 30. Specifically, the control device 21 controls the frequency of the compressor 22, the opening degree of the pressure reducing device 25, the rotation speed of the fan 28, and the frequency (i.e., the rotation speed) of the heat source side pump 30.

[0020] The control device 21 is configured with hardware such as a circuit device that realizes the functions thereof. Alternatively, the control device 21 has a memory that stores a program and a CPU (Central Processing Unit), and the functions of the control device 21 are realized by the CPU executing the program.

[0021] The refrigeration cycle apparatus 20 also includes a heat exchanger differential pressure detection unit 31 that detects the differential pressure between the inlet and outlet sides of the heat medium in the water heat exchanger, i.e., the differential pressure before and after the heat exchanger 26 in the heat source side branch pipe 40a (hereinafter also referred to as heat exchanger differential pressure). The heat exchanger differential pressure detection unit 31 is configured, for example, with a differential pressure gauge. The control device 21 of the refrigeration cycle apparatus 20 is connected to the heat exchanger differential pressure detection unit 31, and the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31 is input to the control device 21. Hereinafter, the heat exchanger differential pressure detection unit 31 may be referred to as a first detection unit.

[0022] In addition, instead of configuring the heat exchanger differential pressure detection unit 31 with a differential pressure gauge, it may be configured with two pressure sensors, each of which is attached before and after the heat exchanger 26, and the heat exchanger differential pressure ΔPhex(i) may be determined in the control device 21.

[0023] The configuration of the heat medium circuit 40 will be described below with reference to Fig. 1. In the example of Fig. 1, two load devices 70 are provided in the load side circuit portion of the heat medium circuit 40. Any number of load devices 70 may be provided in the load side circuit portion in the refrigeration cycle system 10, for example, one or three or more. The load device 70 is, for example, an air conditioner such as an air handling unit or a fan coil unit. The load device 70 has a load side heat exchanger (not shown) that exchanges heat between indoor air and the heat medium circulating through the heat medium circuit 40.

[0024] As shown in FIG. 1, the load side circuit portion of the heat medium circuit 40 includes a plurality of load side branch pipes 40b connected in parallel to each other, each of which is provided with a load device 70, and a second return side header pipe 42b to which the downstream ends of the plurality of load side branch pipes 40b are connected. The load side circuit portion of the heat medium circuit 40 also includes a junction pipe 40c that connects the second return side header pipe 42b to a first return side header pipe 42a described later. Each load side branch pipe 40b is provided with a load side expansion valve 71, which is, for example, a proportional two-way valve. The load side expansion valve 71 is provided on the side of the load side branch pipe 40b where the heat medium flows out from the load device 70, that is, between the load device 70 and the second return side header pipe 42b. The junction pipe 40c is also provided with a load side flow meter 73 that detects the flow rate of the heat medium flowing through the load side circuit portion of the heat medium circuit 40 (hereinafter also referred to as the load side flow rate). In the refrigeration cycle system 10 of the first embodiment, the load side flow meter 73 may be omitted.

[0025] 1, the heat source side circuit portion of the heat medium circuit 40 includes a first return water side header pipe 42a connected to a second return water side header pipe 42b via a junction pipe 40c, a supply water side header pipe 41 to which the upstream ends of the multiple load side branch pipes 40b are connected, and multiple heat source side branch pipes 40a each provided with a heat exchanger 26 and a heat source side pump 30. The downstream ends of the multiple heat source side branch pipes 40a are connected to the supply water side header pipe 41, and the upstream ends of the multiple heat source side branch pipes 40a are connected to the first return water side header pipe 42a.

[0026] The first return water side header pipe 42a distributes the heat medium returning from the load side circuit portion to the multiple heat source side branch pipes 40a. Each heat source side pump 30 pumps the heat medium distributed by the first return water side header pipe 42a to a water heat exchanger (heat exchanger 26). The heat medium pumped by the heat source side pump 30 to the heat exchanger 26 is cooled by exchanging heat with the refrigerant in the refrigerant circuit 27 in the heat exchanger 26. The heat medium cooled in each of the multiple heat exchangers 26 flows into the supply water side header pipe 41. The supply water side header pipe 41 merges the heat medium cooled in each of the multiple refrigeration cycle devices 20 and flowing into the supply water side header pipe 41, and distributes and supplies the heat medium to the multiple load devices 70 provided downstream.

[0027] The heat medium circuit 40 also has a bypass pipe 80 that bypasses the load side circuit portion (i.e., bypasses the multiple load devices 70). The bypass pipe 80 connects the supply water side header pipe 41 and the first return water side header pipe 42a that are provided before and after the multiple refrigeration cycle devices 20 in the heat medium circuit 40, respectively.

[0028] The refrigeration cycle system 10 of the first embodiment shown in FIG. 1 employs a single pump system in which the heat source pump 30 is provided only in the heat source side circuit portion of the heat medium circuit 40, and no pump is provided in the load side circuit portion. The bypass piping 80 is provided with a bypass valve 81 for adjusting the flow rate of the heat medium flowing through the bypass piping 80. In the single pump system, the differential pressure before and after the bypass piping 80 (hereinafter also referred to as bypass differential pressure), that is, the differential pressure between the forward water header pipe 41 on the upstream side of the bypass piping 80 and the first return water header pipe 42a on the downstream side, is adjusted by the opening degree of the bypass valve 81. The refrigeration cycle system 10 of the first embodiment also includes a bypass differential pressure detection unit 90 for detecting the bypass differential pressure before and after the bypass piping 80. The bypass differential pressure detection unit 90 is composed of, for example, a differential pressure gauge. Hereinafter, the bypass differential pressure detection unit 90 may be referred to as a second detection unit.

[0029] The refrigeration cycle system 10 includes a system control device 21a that controls the heat medium circuit 40. The system control device 21a is configured with hardware such as a circuit device that realizes its functions. Alternatively, the system control device 21a includes a memory that stores programs and a CPU (Central Processing Unit), and the functions of the system control device 21a are realized by the CPU executing the programs.

[0030] The system controller 21a is connected to the load side flow meter 73, the bypass differential pressure detection unit 90, and the bypass valve 81. The load side flow rate detected by the load side flow meter 73 and the bypass differential pressure detected by the bypass differential pressure detection unit 90 (actual measured value B of the bypass differential pressure) are input to the system controller 21a. The system controller 21a also outputs an instructed opening to the bypass valve 81.

[0031] The inputs to the system control device 21a and the outputs from the system control device 21a are input or output as current signals of, for example, DC 4 to 20 [mA]. ​​In this case, the current of each current signal is a current corresponding to the load side flow rate, the bypass differential pressure, or the instructed opening of the bypass valve 81.

[0032] In addition, instead of using a differential pressure gauge, the bypass differential pressure detection unit 90 may be configured with two pressure sensors, and each pressure sensor may be attached before and after the bypass piping 80, i.e., to the supply water side header pipe 41 and the first return water side header pipe 42a, and the bypass differential pressure may be determined by the system control device 21a.

[0033] In the refrigeration cycle system 10, the control device 21 of the refrigeration cycle device 20 is configured to cooperate with the control devices 21 of the other refrigeration cycle devices 20 to control the operation of the corresponding refrigerant circuit 27 and heat source side pump 30. For the cooperation, one of the multiple refrigeration cycle devices 20 may be set as a representative device, and the control device 21 of this representative device may communicate with each of the control devices 21 of the refrigeration cycle devices 20 other than the representative device. In the example of Fig. 1, the control device 21 of the representative device (the refrigeration cycle device 20 on the lower side in the figure) functions as the system control device 21a.

[0034] The system control device 21a acquires the operation frequency Fp(i) of the heat source pump 30 and the differential pressure (heat exchanger differential pressure ΔPhex(i)) before and after the heat exchanger 26 from each refrigeration cycle device 20. As described above, the load side flow rate is input from the load side flow meter 73 to the system control device 21a, and the bypass differential pressure (actual measurement value B of the bypass differential pressure) is input from the bypass differential pressure detection unit 90. The system control device 21a outputs an opening command to the bypass valve 81 according to the operation frequency Fp(i) of the multiple refrigeration cycle devices 20 acquired and the actual measurement value B of the bypass differential pressure. The bypass valve 81 adjusts the opening according to the opening command from the system control device 21a. As a result, the flow rate of the heat medium flowing from the forward water side header pipe 41 to the first return water side header pipe 42a through the bypass piping 80 is adjusted, and the difference between the flow rate of the heat medium flowing to each refrigeration cycle device 20, which is a heat source device, and the flow rate of the heat medium flowing to each load device 70 is adjusted. By making such adjustments, the pressure difference between the supply water header pipe 41 and the first return water header pipe 42a, i.e., the bypass differential pressure, is adjusted. However, the bypass differential pressure is detected by the bypass differential pressure detection unit 90 even after the adjustments.

[0035] In the refrigeration cycle system 10 of the present disclosure, the system control device 21a judges the scale accumulation state of the water heat exchanger (heat exchanger 26) based on the state of the heat medium circuit 40. The refrigeration cycle system 10 includes an alarm unit 99 that notifies the result of the scale accumulation judgment by the system control device 21a. The alarm unit 99 is configured, for example, as a liquid crystal display or a speaker, and displays the result of the scale accumulation judgment. For example, an operator performing periodic inspection can know the result of the scale accumulation judgment of the heat exchanger 26 by checking the result displayed on the alarm unit 99. For example, when the system control device 21a judges that the amount of scale accumulation in the heat exchanger 26 is equal to or greater than a certain amount, the alarm unit 99 may be configured to notify that fact or that cleaning is required.

[0036] FIG. 3 is a diagram showing the relationship between the head loss and the flow rate of the heat exchanger (heat exchanger 26) in FIG. 1. FIG. 4 is a diagram showing the head characteristics of the pump (heat source side pump 30) in FIG. 1. FIG. 5 is a flowchart of the scale deposition determination performed by the system control device 21a in FIG. 1. Hereinafter, based on FIGS. 3 to 5, an example of the scale deposition determination performed by the system control device 21a in the refrigeration cycle system 10 employing a single pump system will be described.

[0037] In the refrigeration cycle system 10 of the first embodiment, the system control device 21a uses the detected value of the heat exchanger differential pressure detector 31 (heat exchanger differential pressure ΔPhex(i)) and the detected value of the bypass differential pressure detector 90 (actual measured value B of the bypass differential pressure) as the state of the heat medium circuit 40 to determine the scale deposition state of the heat exchanger 26.

[0038] In FIG. 3, the horizontal axis represents the flow rate [m 3 / h] of the heat medium flowing through the water heat exchanger (heat exchanger 26), and the vertical axis represents the head loss [kPa] of the heat medium in the water heat exchanger (heat exchanger 26). In FIG. 4, the horizontal axis represents the flow rate Vw of the heat medium that the heat source side pump 30 can deliver, and the vertical axis represents the head pressure P. The head pressure P is the pressure increase amount of the heat medium by the heat source side pump 30 and corresponds to the pump head of the heat source side pump 30. FIG. 4 shows pump head curves C1, C2, and C3 representing the relationship between the flow rate Vw of the heat medium and the head pressure P when the operating frequencies Fp of the heat source side pump 30 are Fp1, Fp2, and Fp3 (Fp1 < Fp2 < Fp3).

[0039] As shown in FIG. 3, when the flow rate of the heat medium flowing through the heat exchanger 26 increases, the head loss, that is, the differential pressure before and after the heat exchanger 26 increases. Also, as shown in FIG. 4, the higher the flow rate Vw of the heat medium delivered by the heat source side pump 30, the lower the head pressure P. For the same flow rate Vw, the higher the operating frequency Fp of the heat source side pump 30, the higher the head pressure P. Also, for the same head pressure P, the higher the operating frequency Fp of the heat source side pump 30, the greater the flow rate Vw.

[0040] During operation after the start of operation of the refrigeration cycle system 10, the system control device 21a calculates a bypass differential pressure using the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31, and compares a difference Dab between a calculated value A of the calculated bypass differential pressure and an actual measurement value B of the bypass differential pressure detected by the bypass differential pressure detection unit 90 with a pre-stored difference value (for example, a difference Dab_0 between the calculated value A and the actual measurement value B obtained in an initial state such as during a test run) to determine a scale accumulation state of the heat exchanger 26. In detail, when the difference during operation deviates by a certain amount or more from the pre-stored difference value, the system control device 21a determines that a certain amount or more of scale has accumulated in the heat exchanger 26, and notifies the fact by the notification unit 99.

[0041] In order to enable calculation of the bypass differential pressure A from the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31, the characteristics of the heat exchanger 26 shown in FIG. 3 and the head characteristics of the heat source side pump 30 shown in FIG. 4 are stored in advance in the system control device 21a in the form of a table or formula.

[0042] For example, the relationship between the head loss in the heat exchanger 26 (i.e., the heat exchanger differential pressure ΔPhex(i)) and the flow rate Vw of the heat medium is stored in the form of the following equation (1). Here, f1(ΔPhex(i)) in equation (1) is a function of the heat exchanger differential pressure ΔPhex(i). The (i) in each parameter means the number of refrigeration cycle devices 20. The flow rate of the heat medium flowing through the heat exchanger 26 is the flow rate of the heat medium flowing through the heat source side pump 30, and is also the flow rate of the heat medium flowing through the refrigeration cycle device 20, which is the heat source machine.

[0043] Vw(i) = f1(ΔPhex(i)) (1)

[0044] Furthermore, for example, the relationship between the operating frequency Fp (i.e., rotation speed), the flow rate Vw(i), and the head pressure P (i.e., pump head ΔPp(i)) of the heat source side pump 30 is stored in the form of the following formula (2). Here, f2(Fp, Vw(i)) in formula (2) is a function of the operating frequency Fp and the flow rate Vw(i) of the heat source side pump 30.

[0045] ΔPp(i) = f2(Fp, Vw(i)) (2)

[0046] 1, in a configuration in which the refrigeration cycle system 10 includes a plurality of refrigeration cycle devices 20, the refrigeration cycle system 10 has heat exchanger differential pressure detection units 31 (see FIG. 2) in the same number as the number of the refrigeration cycle devices 20. In this case, the system control device 21a uses the heat exchanger differential pressure ΔPhex(i) detected by the plurality of heat exchanger differential pressure detection units 31 and the actual measurement value B of the bypass differential pressure detected by one bypass differential pressure detection unit 90 to determine scale deposition.

[0047] (During test run of refrigeration cycle system 10) During a trial run immediately after constructing the refrigeration cycle system 10, there is no scale in the water heat exchanger (heat exchanger 26). In this initial state, the system control device 21a acquires the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31 and the operation frequency Fp of the heat source side pump 30 from the control devices 21 of the multiple refrigeration cycle devices 20. In addition, the system control device 21a receives an actual measurement value B of the bypass differential pressure from the bypass differential pressure detection unit 90. The system control device 21a calculates the flow rate of the heat medium flowing in the heat exchanger 26, i.e., the flow rate Vw(i) of the heat medium flowing through the refrigeration cycle device 20, from the acquired heat exchanger differential pressure ΔPhex(i) using equation (1). Furthermore, the system control device 21a calculates the pump head ΔPp(i) from the calculated flow rate Vw(i) and the acquired operation frequency Fp (i.e., the rotation speed) of the heat source side pump 30 using equation (2). The system control device 21a calculates the pump head ΔPp(i) using equations (1) and (2) for each of the multiple refrigeration cycle devices 20. Then, the system control device 21a calculates an average value of the differences between the pump head ΔPp(i) and the heat exchanger differential pressure ΔPhex(i) in each refrigeration cycle device 20 using the following equation (3), and sets the calculated average value as the bypass differential pressure calculation value A.

[0048] A=Ave(ΔPp(i)-ΔPhex(i))···(3)

[0049] In other words, the calculated value A of the bypass differential pressure is the average of the pressure differences (ΔPp(i)-ΔPhex(i)) before and after the refrigeration cycle device 20 in the heat source side branch pipe 40a for all the heat source side branch pipes 40a. Then, the system control device 21a calculates the difference between the calculated value A of the bypass differential pressure obtained using equation (3), i.e., the bypass differential pressure calculated based on the state of the heat source side circuit part of the heat medium circuit 40, and the actual measured value B of the bypass differential pressure directly detected by the bypass differential pressure detection unit 90, and stores it as the initial state difference Dab_0.

[0050] (When the refrigeration cycle system 10 is in operation) During operation of the refrigeration cycle system 10 after the start of operation, the amount of scale buildup in the heat exchangers 26 gradually increases. During operation of the refrigeration cycle system 10 after the start of operation, the system control device 21a acquires each heat exchanger differential pressure ΔPhex(i) and an actual measurement value B of the bypass differential pressure, calculates a calculated value A of the bypass differential pressure, and obtains a difference between the calculated value A and the actual measurement value B, as in the test run. Then, during operation of the refrigeration cycle system 10 after the start of operation, the system control device 21a determines the scale buildup state for the multiple heat exchangers 26 by comparing the difference obtained during operation with the difference obtained in the initial state.

[0051] A flow of scale accumulation determination performed by the system control device 21a during operation after the start of operation of the refrigeration cycle system 10 will be described with reference to Fig. 5. During operation of the refrigeration cycle system 10, the system control device 21a acquires the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31 from each control device 21 of the multiple refrigeration cycle devices 20 (step S10). The system control device 21a also acquires the operation frequency Fp of the heat source side pump 30 from each control device 21 of the multiple refrigeration cycle devices 20. The system control device 21a also receives an actual measurement value B of the bypass differential pressure from the bypass differential pressure detection unit 90.

[0052] The system control device 21a calculates the flow rate Vw(i) of the heat medium flowing through the heat exchanger 26, i.e., the flow rate of the heat medium flowing through the refrigeration cycle device 20, for each refrigeration cycle device 20 from the acquired heat exchanger differential pressure ΔPhex(i) using equation (1) (step S11). Furthermore, the system control device 21a calculates the pump head ΔPp(i) using equation (2) from the flow rate Vw(i) calculated in step S11 and the acquired operation frequency Fp of the heat source side pump 30 (step S12). The system control device 21a performs the calculations of steps S11 and S12 for each refrigeration cycle device 20, and obtains a calculated value A of the bypass differential pressure using equation (3) from the pump head ΔPp(i) calculated in step S12 and the heat exchanger differential pressure ΔPhex(i) acquired in step S10 (step S13).

[0053] The calculated value A of the bypass differential pressure obtained here reflects the state of the flow path of the heat medium in the heat exchangers 26 of the multiple refrigeration cycle devices 20 at this time. When the amount of scale deposition in the heat exchangers 26 of the multiple refrigeration cycle devices 20 increases, the head loss of the heat medium in those heat exchangers 26 (i.e., the heat exchanger differential pressure ΔPhex(i)) increases due to friction, etc., so the flow rate [m 3 / h] increases, and the head pressure P of the heat source side pump 30 (i.e., the pump head ΔPp(i)) decreases. Therefore, when the amount of scale deposition increases, the pump head ΔPp(i) decreases and the heat exchanger differential pressure ΔPhex(i) increases, so the calculated bypass differential pressure A decreases.

[0054] The system control device 21a calculates the difference Dab between the calculated value A of the bypass differential pressure calculated in step S13 and the actual measured value B of the bypass differential pressure input from the bypass differential pressure detection unit 90 (step S14). Then, the system control device 21a judges whether or not this difference Dab obtained during operation deviates from a pre-stored difference value (i.e., the difference Dab_0 obtained in the initial state) by a certain amount or more (step S15). If the difference Dab during operation deviates from the difference Dab_0 in the initial state by a certain amount or more (step S15; YES), the system control device 21a judges that a certain amount or more of scale has accumulated in the multiple heat exchangers 26 of the refrigeration cycle system 10 and notifies the fact by the notification unit 99 or the like (step S16).

[0055] Here, when the difference Dab during operation deviates by a certain amount or more from the difference Dab_0 in the initial state, the determination may be made based on the absolute value of the difference obtained by subtracting the difference Dab_0 in the initial state from the difference during operation, regardless of whether the value is positive or negative.

[0056] Thus, in the refrigeration cycle system 10 of embodiment 1, which is a single pump system, during operation after the start of operation, the system control device 21a calculates the difference Dab between the calculated value A of the bypass differential pressure and the actual measured value B, and compares the calculated difference Dab during operation with the initial state difference Dab_0 calculated and stored in advance during trial operation, and the state of scale accumulation on the heat exchanger 26 over time can be determined based on the comparison result.

[0057] Furthermore, the criterion for determining that a certain amount or more of scale has accumulated in the multiple heat exchangers 26 of the refrigeration cycle system 10 may be determined, for example, by learning the difference Dab and determining the difference Dab based on the learned difference Dab. In this case, the system control device 21a has a function of storing and learning the calculated value A, the measured value B, and the difference Dab therebetween. The system control device 21a learns the difference Dab in the process of operating the refrigeration cycle system 10 and determines the scale accumulation state based on the learned difference Dab.

[0058] The method of determining the scale deposition state of the heat exchanger 26 is not limited to the example in Fig. 5. In the example in Fig. 5, the pump head ΔPp(i) of the heat source side pump 30 is calculated from the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31, the bypass differential pressure is calculated based on the heat exchanger differential pressure ΔPhex(i) and the calculated pump head ΔPp(i), and the scale deposition state is determined based on the difference Dab between the calculated value A of the calculated bypass differential pressure and the actual measured value B of the bypass differential pressure detected by the bypass differential pressure detection unit 90. In the following, a method of determining the scale deposition state by comparing a calculated value C obtained by a method different from the calculated value A instead of the actual measured value B with the calculated value A will be described.

[0059] Fig. 6 is a circuit diagram showing a modified example of the refrigeration cycle device 20 of Fig. 2. In Fig. 6, the solid white arrows indicate the direction in which the refrigerant flows, and the dashed white arrows indicate the direction in which the heat medium flows.

[0060] In the refrigeration cycle device 20 of Fig. 6, the heat source side branch pipe 40a is provided with a heat exchanger differential pressure detection unit 31 that detects the differential pressure before and after the heat exchanger 26, and a pump differential pressure detection unit 32 that detects the pump differential pressure before and after the heat source side pump 30 (i.e., the pump head). The pump differential pressure detection unit 32 is, for example, a differential pressure gauge. In the example of Fig. 6, the heat exchanger differential pressure detection unit 31 may be referred to as a first detection unit, and the pump differential pressure detection unit 32 may be referred to as a second detection unit. Instead of using a differential pressure gauge as the pump differential pressure detection unit 32, two pressure sensors provided before and after the heat source side pump 30 may be used.

[0061] The system control device 21a determines the bypass differential pressure using the following formula (4) to obtain the calculated value C. The pump head ΔPp(i), which is a parameter of the calculated value A, is calculated from the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31 using formulas (1) and (2), but ΔPp_a(i) in formula (4) for determining the calculated value C is the actual pump head value detected directly by the pump differential pressure detection unit 32.

[0062] C=Ave(ΔPp_a(i)-ΔPhex(i))···(4)

[0063] During a test run of the refrigeration cycle system 10, the system control device 21a calculates the bypass differential pressures A and C, respectively, calculates the difference therebetween, and stores the difference therebetween as the initial state difference Dac_0. During operation after the start of operation of the refrigeration cycle system 10, the system control device 21a calculates the bypass differential pressures A and C, respectively, calculates the difference Dac therebetween, and determines the scale accumulation state of the heat exchanger 26 by comparing the difference Dac during operation with the difference Dac_0 in the initial state.

[0064] In this manner, in a configuration in which the heat exchanger differential pressure detection unit 31 and the pump differential pressure detection unit 32 are used for scale buildup determination, a second detection unit (pump differential pressure detection unit 32) is required for each of the refrigeration cycle devices 20. On the other hand, in a configuration in which the heat exchanger differential pressure detection unit 31 and the bypass differential pressure detection unit 90 are used for scale buildup determination as in Fig. 1 to Fig. 5, it is sufficient to provide one second detection unit (the bypass differential pressure detection unit 90 in Fig. 1) regardless of the number of the refrigeration cycle devices 20, and therefore the structure of the refrigeration cycle system 10 can be simplified.

[0065] As described above, the refrigeration cycle system 10 according to the first embodiment includes the refrigerant circuit 27 having the compressor 22 and circulating the refrigerant by the compressor 22, the heat medium circuit 40 having the heat source side pump 30 and circulating the heat medium by the heat source side pump 30, the heat exchanger 26 performing heat exchange between the refrigerant and the heat medium, and the system control device 21a controlling the heat source side pump 30. The heat medium circuit 40 includes the load device 70 provided downstream of the heat exchanger 26 and the bypass piping 80 bypassing the load device 70. The refrigeration cycle system 10 also includes a first detection unit (heat exchanger differential pressure detection unit 31) provided in the heat medium circuit 40 for detecting the differential pressure before and after the heat exchanger 26, and a second detection unit (bypass differential pressure detection unit 90) provided in the heat medium circuit 40 for detecting the bypass differential pressure before and after the bypass piping 80. The system control device 21a obtains the head (ΔPp(i)) of the heat source side pump 30 from the differential pressure (heat exchanger differential pressure ΔPhex(i)) detected by the first detection unit and the rotation speed (e.g., operating frequency Fp) of the heat source side pump 30, and calculates the bypass differential pressure before and after the bypass piping 80 based on the differential pressure (heat exchanger differential pressure ΔPhex(i)) and the head (ΔPp(i)). The system control device 21a determines the scale deposition state of the heat exchanger 26 by comparing the difference Dab between the calculated value A of the calculated bypass differential pressure and the actual measured value B of the bypass differential pressure detected by the second detection unit with a pre-stored difference value (e.g., difference Dab_0 in the initial state).

[0066] In this way, in the refrigeration cycle system 10 according to the first embodiment, the difference Dab between the calculated value A and the measured value B of the bypass differential pressure obtained by different methods using the first and second detection units provided in the heat medium circuit 40 is compared with the difference value stored in advance to determine the scale deposition state of the heat exchanger 26. Since both the first and second detection units are provided in the heat medium circuit 40 where scale is deposited, the configuration of the present disclosure that determines the scale deposition state of the heat exchanger 26 based on the difference Dab between the calculated value A and the measured value B of the bypass differential pressure obtained using the detection values ​​(heat exchanger differential pressure ΔPhex(i) and the measured value B of the bypass differential pressure) can perform a more accurate determination that is less affected by load fluctuations and fluctuations in operating conditions than a conventional configuration that determines the scale deposition state of the heat exchanger based on the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the heat exchanger.

[0067] 6, the refrigeration cycle system 10 includes a refrigerant circuit 27 having a compressor 22 and circulating a refrigerant by the compressor 22, a heat medium circuit 40 having a heat source side pump 30 and circulating a heat medium by the heat source side pump 30, a heat exchanger 26 performing heat exchange between the refrigerant and the heat medium, and a system control device 21a controlling the heat source side pump 30, and the heat medium circuit 40 includes a load device 70 provided downstream of the heat exchanger 26 and a bypass piping 80 bypassing the load device 70. The refrigeration cycle system 10 also includes a first detection unit (heat exchanger differential pressure detection unit 31) provided in the heat medium circuit 40 for detecting a differential pressure before and after the heat exchanger 26, and a second detection unit (pump differential pressure detection unit 32) provided in the heat medium circuit 40 for detecting a pump differential pressure before and after the heat source side pump 30. The system control device 21a determines the head (ΔPp(i)) of the heat source side pump 30 from the differential pressure (heat exchanger differential pressure ΔPhex(i)) detected by the first detection unit and the rotation speed (e.g., operating frequency Fp) of the heat source side pump 30, calculates the bypass differential pressure before and after the bypass piping based on the differential pressure (heat exchanger differential pressure ΔPhex(i)) and the head (ΔPp(i)) to obtain a first calculated value (calculated value A), and calculates the bypass differential pressure before and after the bypass piping 80 based on the differential pressure (heat exchanger differential pressure ΔPhex(i)) detected by the first detection unit and the pump differential pressure (actual measured head value ΔPp_a(i)) detected by the second detection unit to obtain a second calculated value (calculated value C). Then, the system control device 21a determines the scale deposition state of the heat exchanger 26 by comparing the difference Dac between the first calculated value (calculated value A) and the second calculated value (calculated value C) of the bypass differential pressure with a pre-stored difference value (Dac_0 in the initial state).

[0068] 6, the scale buildup state of the heat exchanger 26 is determined by comparing the difference Dac between the first calculated value (calculated value A) and the second calculated value (calculated value C) of the bypass differential pressure obtained by different methods using the first detection unit and the second detection unit provided in the heat medium circuit 40 with a pre-stored difference value (initial state difference Dac_0). Since both the first detection unit and the second detection unit are provided in the heat medium circuit 40 where scale buildup occurs, the configuration of the present disclosure that determines the scale buildup state of the heat exchanger 26 based on the difference Dac between the first calculated value and the second calculated value of the bypass differential pressure obtained using the detection values ​​(heat exchanger differential pressure ΔPhex(i) and the actual measured value ΔPp_a(i) of the head) is less affected by load fluctuations and operating condition fluctuations and can perform more accurate determination than a conventional configuration that determines the scale buildup state of the heat exchanger based on the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the heat exchanger.

[0069] Furthermore, the system control device 21a stores, as a pre-stored difference value, the difference Dac_0 calculated in the initial state where there is no scale in the heat exchanger 26. Therefore, since the scale accumulation during operation can be determined using the initial state obtained in the configuration of the refrigeration cycle system, the accuracy of the determination is improved.

[0070] The refrigeration cycle system 10 includes a plurality of refrigeration cycle devices 20, each having a refrigerant circuit 27, a heat source side pump 30, and a heat exchanger 26. The heat medium circuit 40 includes a plurality of heat source side branch pipes 40a in which the heat source side pumps 30 and the heat exchangers 26 of each refrigeration cycle device 20 are provided. The plurality of heat source side branch pipes 40a are connected in parallel to each other and connected to the load side.

[0071] Even when the refrigeration cycle system 10 includes multiple refrigeration cycle devices 20 in this manner, the scale deposition state of the multiple heat exchangers 26 can be determined from the state of the heat medium circuit 40, just as in the case where the refrigeration cycle system 10 includes only one refrigeration cycle device 20.

[0072] The refrigeration cycle system 10 also includes an alarm unit 99 having a display or a speaker. The system control device 21a is configured to cause the alarm unit 99 to notify the user that scale has accumulated when the difference Dab (or the difference Dac) deviates from a pre-stored difference value by a certain amount or more.

[0073] As a result, for example, an operator performing regular inspections can know when the amount of scale on the heat exchanger 26 reaches a certain level, and when notified, can take measures such as cleaning the heat exchanger 26, thereby avoiding the occurrence of abnormalities such as clogging of the heat exchanger 26 due to scale or an extreme drop in heat exchange efficiency.

[0074] Embodiment 2 FIG. 7 is a circuit diagram showing a schematic configuration of a refrigeration cycle system 110 according to a second embodiment of the present disclosure. The refrigeration cycle system 10 of the first embodiment employs a single pump system, whereas the refrigeration cycle system 110 of the second embodiment employs a dual pump system. In addition, in the refrigeration cycle system 110 of the second embodiment, the second detection unit used to determine the scale accumulation state is different from that in the first embodiment. The circuit configuration of the refrigeration cycle system 110 of the second embodiment will be described with reference to FIG. 7. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals and their description will be omitted, and the differences from the first embodiment will be mainly described.

[0075] As shown in Fig. 7, in a refrigeration cycle system 110 employing a dual pump system, a pump is provided in each of a heat source side circuit portion and a load side circuit portion of a heat medium circuit 140. Hereinafter, a pump provided in the heat source side circuit portion is referred to as a heat source side pump 30, and a pump provided in the load side circuit portion is referred to as a load side pump 144. In the second embodiment, a pipe that bypasses the load side circuit portion in the heat medium circuit 140, i.e., bypasses a plurality of load devices 70, is a free bypass pipe 180 that does not have a bypass valve 81 (see Fig. 1).

[0076] The configuration of the heat source side circuit portion of the heat medium circuit 140 is the same as that of the first embodiment shown in Fig. 1. The heat source side circuit portion has a plurality of heat source side branch pipes 140a each provided with a heat exchanger 26 and a heat source side pump 30, a first return water side header pipe 142a to which the upstream ends of the plurality of heat source side branch pipes 140a are connected, and a first supply water side header pipe 141a to which the downstream ends of the plurality of heat source side branch pipes 140a are connected.

[0077] The load side circuit portion of the heat medium circuit 140, like in the first embodiment shown in FIG. 1, includes a plurality of load side branch pipes 140b, each of which is provided with a load device 70 and a load side expansion valve 71, a second return water side header pipe 142b to which the downstream ends of the plurality of load side branch pipes 140b are connected, a junction pipe 140c connecting this second return water side header pipe 142b and a first return water side header pipe 142a on the heat source unit side, and a load side flow meter 73 provided on the junction pipe 140c. However, in the heat medium circuit 140 of embodiment 2, the supply water side header pipe 141 has a first supply water side header pipe 141a on the heat source unit (refrigeration cycle device 20) side and a second supply water side header pipe 141b on the load device 70 side, and the first supply water side header pipe 141a and the second supply water side header pipe 141b are connected by a connection piping 140d in which a load side pump 144 is provided.

[0078] In the example of Fig. 7, the refrigeration cycle system 10 is configured to distribute and circulate the heat medium cooled by four refrigeration cycle devices 20 to two load devices 70. In detail, the heat medium circuit 40 is configured to sequentially connect four heat source side branch pipes 40a, a first forward water side header pipe 141a, three connection pipes 140d, a second forward water side header pipe 141b, two load side branch pipes 140b, a second return water side header pipe 142b, a junction pipe 140c, and a first return water side header pipe 142a. Two of the three connection pipes 140d are provided with load side pumps 144 that pump the heat medium from the first forward water side header pipe 141a on the heat source side to the second forward water side header pipe 141b on the load side. Furthermore, the remaining one of the three connecting pipes 140d is provided with a forward water expansion valve 145, which is, for example, a proportional two-way valve.

[0079] The system controller 21a is connected to a load side flow meter 73, and the load side flow rate detected by the load side flow meter 73 is input to the system controller 21a. In addition, a load side pump 144 and a supply water side expansion valve 145 are each connected to the system controller 21a, and the system controller 21a is configured to control the frequency of the load side pump 144 and the opening degree of the supply water side expansion valve 145.

[0080] In the heat medium circuit 140, the free bypass piping 180 connects the first forward water header pipe 141a and the first return water header pipe 142a, which are both ends of the circuit portion on the heat source side. When the flow rate of the heat medium flowing through each water heat exchanger (heat exchanger 26) is greater than the flow rate of the heat medium flowing through each load device 70, the free bypass piping 180 causes the heat medium equivalent to the difference between the flow rates to bypass the two load devices 70 and flow from the first forward water header pipe 141a to the first return water header pipe 142a.

[0081] In the refrigeration cycle system 110 of the second embodiment, similarly to the first embodiment, the system control device 121a determines the scale deposition state of the water heat exchanger (heat exchanger 26) based on the state of the heat medium circuit 140. In the first embodiment, the differential pressure before and after the heat exchanger 26 detected by the heat exchanger differential pressure detection unit 31 and the bypass differential pressure before and after the bypass piping 80 detected by the bypass differential pressure detection unit 90 are used as the state of the heat medium circuit 40, but in the second embodiment, the differential pressure before and after the heat exchanger 26 detected by the heat exchanger differential pressure detection unit 31 and the flow rate of the heat medium flowing on the load side detected by the load side flow meter 73 (hereinafter also referred to as the load side flow rate) are used as the state of the heat medium circuit 40. That is, in the second embodiment, the first detection unit is the heat exchanger differential pressure detection unit 31, and the second detection unit is the load side flow meter 73.

[0082] (During test run of the refrigeration cycle system 110) During a trial run immediately after constructing the refrigeration cycle system 110, no scale has accumulated in the water heat exchanger (heat exchanger 26). In this initial state, the system control device 121a acquires the differential pressures (heat exchanger differential pressure ΔPhex(i)) across the heat exchanger 26 detected by the heat exchanger differential pressure detection units 31 from the control devices 21 of the multiple refrigeration cycle devices 20. In addition, the actual measured value FB of the load side flow rate detected by the load side flow meter 73 is input to the system control device 121a.

[0083] The system controller 121a first calculates a bypass differential pressure calculation value A from the acquired heat exchanger differential pressures ΔPhex(i) using equations (1) to (3). That is, the system controller 21a calculates the flow rate through the heat exchanger 26, i.e., the flow rate Vw(i) through the refrigeration cycle device 20, from the acquired heat exchanger differential pressures ΔPhex(i) using equation (1), calculates the pump head ΔPp(i) from the flow rate Vw(i) using equation (2), and obtains the bypass differential pressure calculation value A from the pump head ΔPp(i) and the heat exchanger differential pressure ΔPhex(i) using equation (3).

[0084] Then, the system control device 121a uses the calculated value A of the bypass differential pressure and the Cv value (hereinafter referred to as Cv) of the free bypass piping 180 that has been learned in advance to calculate the bypass flow rate flowing through the free bypass piping 180 from the following equation (5), thereby obtaining a calculated value BFa.

[0085] BFa = Cv × (A [kPa]^0.5) (5)

[0086] Here, the Cv value of the free bypass piping 180 is learned during the test run to obtain the learned Cv value. Since the Cv value of the free bypass piping 180 basically does not change except in special cases such as when a failure occurs, the value learned during the test run can be used after the start of operation.

[0087] Furthermore, the system control device 121a obtains the load side flow rate flowing through the load side from the following formula (6) using the calculated bypass flow rate BFa and the flow rate Vw(i) of the heat medium flowing through each refrigeration cycle device 20, to obtain a calculated value FA. Specifically, the calculated bypass flow rate BFa obtained from formula (5) is subtracted from the total flow rate of the heat medium flowing through each refrigeration cycle device 20 for all the refrigeration cycle devices 20 of the refrigeration cycle system 10 to obtain the calculated flow rate FA of the heat medium flowing through the load side.

[0088] FA = Total(Vw(i)) - BFa (6)

[0089] The system control device 21a calculates the difference between the calculated value FA of the load side flow rate obtained by equation (6), i.e., the load side flow rate obtained from the state of the circuit part on the heat source side of the heat medium circuit 40, and the actual measured value FB of the load side flow rate detected by the load side flow meter 73, and stores the calculated difference as the initial state difference Dfab_0.

[0090] (When the refrigeration cycle system 110 is in operation) During operation of the refrigeration cycle system 110 after the start of operation, the amount of scale buildup in the heat exchanger 26 gradually increases. During operation of the refrigeration cycle system 110 after the start of operation, the system control device 121a acquires each heat exchanger differential pressure ΔPhex(i) and the actual load side flow rate FB, calculates a calculated load side flow rate FA, and obtains a difference Dfab between the calculated value FA and the actual value FB, as in the test run. During operation of the refrigeration cycle system 110 after the start of operation, the system control device 121a compares the difference Dfab obtained during operation with the difference Dfab_0 obtained during the test run to determine the scale buildup state for the multiple heat exchangers 26.

[0091] FIG. 8 is a flow chart of scale deposition judgment performed by the system control device 121a of FIG. 7. Based on FIG. 8, a flow of scale deposition judgment performed by the system control device 121a during operation after the start of operation of the refrigeration cycle system 110 will be described. During operation of the refrigeration cycle system 110, the system control device 121a acquires the heat exchanger differential pressure ΔPhex(i) detected by the heat exchanger differential pressure detection unit 31 (see FIG. 2) from the control devices 21 of the multiple refrigeration cycle devices 20 (step S20). In addition, the system control device 121a acquires the operation frequency Fp (i.e., the rotation speed) of the heat source side pump 30 from the control devices 21 of the multiple refrigeration cycle devices 20. In addition, the system control device 121a receives an actual measurement value FB of the flow rate of the heat medium flowing through the junction pipe 40c on the load side, i.e., the load side flow rate, from the load side flow meter 73.

[0092] The system control device 121a calculates the flow rate of the heat medium flowing through the heat exchanger 26 from the heat exchanger differential pressure ΔPhex(i) for each refrigeration cycle device 20, i.e., the flow rate Vw(i) of the heat medium flowing through the refrigeration cycle device 20, using equation (1) (step S21). Furthermore, the system control device 121a calculates the pump head ΔPp(i) from the flow rate Vw(i) calculated in step S21 and the operating frequency Fp (i.e., the rotation speed) of the heat source side pump 30 obtained, using equation (2) (step S22). The system control device 121a performs the calculations of steps S11 and S22 for each refrigeration cycle device 20, and obtains a calculation value A of the bypass differential pressure from the pump head ΔPp(i) calculated in step S22 and the heat exchanger differential pressure ΔPhex(i) obtained in step S20, using equation (3) (step S23). Furthermore, the system controller 121a calculates the bypass flow rate using equation (5) from the calculated value A of the bypass differential pressure and the previously learned Cv value of the free bypass piping 180, and obtains a calculated value BFa (step S23). The system controller 121a calculates the load side flow rate using equation (6) from the flow rate Vw(i) calculated in step S21 for each refrigeration cycle device 20 and the calculated value BFa of the bypass flow rate calculated in step S23, and obtains a calculated value FA (step S24).

[0093] The calculated value FA of the load side flow rate obtained here reflects the state of the flow path of the heat medium in the heat exchangers 26 of the multiple refrigeration cycle devices 20 at this time. When the amount of scale deposition increases in the heat exchangers 26 of the multiple refrigeration cycle devices 20, the head loss of the heat medium in those heat exchangers 26 (i.e., the heat exchanger differential pressure ΔPhex(i)) increases due to friction, etc., so the flow rate [m 3 / h] increases, and the head pressure P of the heat source side pump 30 (i.e., the pump head ΔPp(i)) decreases. Therefore, when the amount of scale deposition increases, the pump head ΔPp(i) decreases and the heat exchanger differential pressure ΔPhex(i) increases, so the calculated bypass differential pressure A decreases and the calculated load side flow rate FA increases.

[0094] The system controller 121a calculates a difference Dfab between the calculated load-side flow rate FA calculated in step S24 and the measured load-side flow rate FB detected by the load-side flow meter 73 (step S25). Then, the system controller 121a judges whether or not this difference Dfab obtained during operation deviates from the pre-stored difference Dfab_0 (i.e., the difference Dfab_0 obtained in the initial state) by a certain amount or more (step S26). If the difference Dfab during operation deviates from the difference Dfab_0 in the initial state by a certain amount or more (step S26; YES), the system controller 121a judges that a certain amount or more of scale has accumulated in the multiple heat exchangers 26 of the refrigeration cycle system 110 and notifies the fact by the notification unit 99 or the like (step S27).

[0095] Here, a case in which the difference Dfab during operation deviates by a certain amount or more from the difference Dfab_0 in the initial state may be determined by the absolute value of the difference Dfab during operation minus the difference Dfab_0 in the initial state, regardless of whether the difference is positive or negative.

[0096] In this manner, in the refrigeration cycle system 110 of embodiment 2 which is a dual pump system, during operation after the start of operation, the system control device 21a calculates the difference Dfab between the calculated load side flow rate FA and the actual measured value FB, and compares the calculated difference Dfab during operation with the initial state difference Dfab_0 calculated and stored in advance during trial operation, and the state of scale accumulation in the heat exchanger 26 over time can be determined based on the comparison result.

[0097] Instead of the measured value FB of the load side flow rate, a calculated value FC of the load side flow rate obtained by a method other than the calculated value FA can be used to perform the scale accumulation judgment. For example, as shown in FIG. 6, a heat exchanger differential pressure detection unit 31 and a pump differential pressure detection unit 32 are provided in the heat source side branch pipe 40a of each refrigeration cycle device 20, and the calculated value FC of the load side flow rate is obtained from the formulas (4) to (6) using the detected values. The system control device 121a calculates a difference Dfac between the calculated value FA of the load side flow rate obtained from the formulas (1) to (3), (5), and (6) and the calculated value FC of the load side flow rate. If this difference Dfac deviates from the difference Dfac_0 calculated during the trial operation by a certain amount or more, it is determined that a certain amount or more of scale has accumulated in the multiple heat exchangers 26 of the refrigeration cycle system 110, and an alarm unit 99 or the like is used to alarm the fact.

[0098] As described above, the refrigeration cycle system 110 according to the second embodiment includes the refrigerant circuit 27 having the compressor 22 and circulating the refrigerant by the compressor 22, the heat medium circuit 40 having the heat source side pump 30 and the load side pump 144 and circulating the heat medium by the heat source side pump 30 and the load side pump 144, the heat exchanger 26 performing heat exchange between the refrigerant and the heat medium, and the system control device 121a controlling the heat source side pump 30. The heat medium circuit 40 includes the load device 70 provided downstream of the heat exchanger 26, and the free bypass piping 180 bypassing the load device 70. The heat source side pump 30 pumps the heat medium to the heat exchanger 26, and the load side pump 144 pumps the heat medium to the load device 70. The refrigeration cycle system 110 is provided with a first detector (heat exchanger differential pressure detector 31) that is provided in the heat medium circuit 40 and detects the pressure difference before and after the heat exchanger 26, and a second detector (load side flow meter 73) that is provided on the load side of the heat medium circuit 40 and detects the load side flow rate of the heat medium. The system control device 121a obtains the head (ΔPp(i)) of the heat source side pump 30 from the differential pressure (heat exchanger differential pressure ΔPhex(i)) detected by the first detector and the rotation speed (for example, the operating frequency Fp) of the heat source side pump 30, and calculates the load side flow rate of the heat medium flowing on the load side of the heat medium circuit 40 based on the differential pressure (heat exchanger differential pressure ΔPhex(i)) and the head (ΔPp(i)). The system control device 121a determines the state of scale deposition in the heat exchanger 26 by comparing the difference Dfab between the calculated value FA of the load side flow rate and the actual measured value FB of the load side flow rate detected by the second detection unit with a pre-stored difference value (e.g., the difference Dfab_0 in the initial state).

[0099] In this way, in the refrigeration cycle system 110 according to the second embodiment, the difference Dfab between the calculated value A and the measured value B of the load side flow rate obtained by different methods using the first and second detection units provided in the heat medium circuit 40 is compared with the difference value stored in advance to determine the scale deposition state of the heat exchanger 26. Since both the first and second detection units are provided in the heat medium circuit 40 where scale is deposited, the configuration of the present disclosure that determines the scale deposition state of the heat exchanger 26 based on the difference Dfab between the calculated value FA and the measured value FB of the load side flow rate obtained using the detection values ​​(heat exchanger differential pressure ΔPhex(i) and the measured value FB of the load side flow rate) can perform a more accurate determination that is less affected by load fluctuations and fluctuations in operating conditions than a conventional configuration that determines the scale deposition state of the heat exchanger based on the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the heat exchanger.

[0100] A modified example of the refrigeration cycle system 110 of the second embodiment (see FIG. 6) includes a refrigerant circuit 27 having a compressor 22 and circulating a refrigerant by the compressor 22, a heat medium circuit 40 having a heat source side pump 30 and a load side pump 144 and circulating a heat medium by the heat source side pump 30 and the load side pump 144, a heat exchanger 26 performing heat exchange between the refrigerant and the heat medium, and a system control device 121a controlling the heat source side pump 30. The heat medium circuit 40 includes a load device 70 provided downstream of the heat exchanger 26, and a free bypass piping 180 bypassing the load device 70. The heat source side pump 30 pumps the heat medium to the heat exchanger 26, and the load side pump 144 pumps the heat medium to the load device 70. The refrigeration cycle system 110 also includes a first detection unit (heat exchanger differential pressure detection unit 31) provided in the heat medium circuit 40 for detecting the pressure difference before and after the heat exchanger 26, and a second detection unit (pump differential pressure detection unit 32) provided in the heat medium circuit 40 for detecting the pump pressure difference before and after the heat source side pump 30. The system control device 121a determines the head (ΔPp(i)) of the heat source side pump 30 from the differential pressure (heat exchanger differential pressure ΔPhex(i)) detected by the first detection unit and the rotation speed (e.g., operating frequency Fp) of the heat source side pump 30, calculates the load side flow rate of the heat medium flowing on the load side of the heat medium circuit 40 based on the differential pressure (heat exchanger differential pressure ΔPhex(i)) and the head (ΔPp(i)) to obtain a first calculated value (calculated value FA), and calculates the load side flow rate of the heat medium flowing on the load side of the heat medium circuit 40 based on the differential pressure detected by the first detection unit and the pump differential pressure (actual measured head value ΔPp_a(i)) detected by the second detection unit to obtain a second calculated value (calculated value FC). Then, the system control device 121a determines the scale deposition state of the heat exchanger 26 by comparing the difference Dfac between the first calculated value and the second calculated value of the load side flow rate with a pre-stored difference value (the difference Dfac_0 in the initial state).

[0101] In this manner, in the modified example of the refrigeration cycle system 110 (see FIG. 6), the difference Dfac between the first calculated value (calculated value FA) and the second calculated value (calculated value FC) of the load side flow rate obtained by different methods using the first detection unit and the second detection unit provided in the heat medium circuit 40 is compared with a pre-stored difference value (initial state difference Dfac_0) to determine the scale accumulation state of the heat exchanger 26. Since both the first detection unit and the second detection unit are provided in the heat medium circuit 40 where scale accumulates, the configuration of the present disclosure that determines the scale accumulation state of the heat exchanger 26 based on the difference Dfac between the first calculated value and the second calculated value of the load side flow rate obtained using the detection values ​​(heat exchanger differential pressure ΔPhex(i) and actual measurement value ΔPp_a(i) of the head) is less affected by load fluctuations and fluctuations in operating conditions than a conventional configuration that determines the scale accumulation state of the heat exchanger based on the temperature difference between the saturation temperature of the refrigerant and the temperature of the heat medium flowing out of the heat exchanger, and can perform a more accurate determination. [Explanation of symbols]

[0102] 10, 110 refrigeration cycle system, 20 refrigeration cycle device, 21 control device, 21a, 121a system control device, 22 compressor, 24 heat exchanger, 25 pressure reducing device, 26 heat exchanger, 27 refrigerant circuit, 28 fan, 30 heat source side pump, 31 heat exchanger differential pressure detection unit, 32 pump differential pressure detection unit, 40, 140 heat medium circuit, 40a, 140a heat source side branch pipe, 40b, 140b load side branch pipe, 40c, 140c junction pipe, 41, 141 forward water side header pipe, 42a, 142a first return water side header pipe, 42b, 142b second return water side header pipe, 70 load device, 71 load side expansion valve, 73 load side flow meter, 80 bypass piping, 81 bypass valve, 90 bypass differential pressure detection unit, 99 An alarm unit, 140d connecting piping, 141a first supply water side header pipe, 141b second supply water side header pipe, 144 load side pump, 145 supply water side expansion valve, 180 free bypass piping.

Claims

1. A refrigeration cycle system comprising: a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor; a heat medium circuit having a heat source side pump and in which a heat medium is circulated by the heat source side pump; a heat exchanger for exchanging heat between the refrigerant and the heat medium; and a system control device for controlling the heat source side pump, wherein the heat medium circuit has a load device provided downstream of the heat exchanger and a bypass piping for bypassing the load device, A first detection unit provided in the heat medium circuit and configured to detect a pressure difference before and after the heat exchanger; a second detection unit provided in the heat medium circuit and configured to detect a bypass differential pressure before and after the bypass piping; The system control device includes: determining a head of the heat source side pump from the differential pressure detected by the first detection unit and a rotation speed of the heat source side pump, and calculating the bypass differential pressure before and after the bypass piping based on the differential pressure and the head; The difference between the calculated value of the bypass differential pressure and the actual measured value of the bypass differential pressure detected by the second detection unit is compared with a pre-stored difference value to determine the scale deposition state of the heat exchanger. Refrigeration cycle system.

2. A refrigeration cycle system comprising: a refrigerant circuit having a compressor and in which a refrigerant is circulated by the compressor; a heat medium circuit having a heat source side pump and in which a heat medium is circulated by the heat source side pump; a heat exchanger for exchanging heat between the refrigerant and the heat medium; and a system control device for controlling the heat source side pump, wherein the heat medium circuit has a load device provided downstream of the heat exchanger and a bypass piping for bypassing the load device, A first detection unit provided in the heat medium circuit and configured to detect a pressure difference before and after the heat exchanger; a second detection unit provided in the heat medium circuit and detecting a pump pressure difference between before and after the heat source pump; The system control device includes: determining a head of the heat source side pump from the differential pressure detected by the first detection unit and a rotation speed of the heat source side pump, calculating a bypass differential pressure before and after the bypass piping based on the differential pressure and the head to obtain a first calculated value, and calculating the bypass differential pressure before and after the bypass piping based on the differential pressure detected by the first detection unit and the pump differential pressure detected by the second detection unit to obtain a second calculated value; The difference between the first calculated value and the second calculated value of the bypass differential pressure is compared with a previously stored difference value to determine the scale buildup state of the heat exchanger. Refrigeration cycle system.

3. A refrigeration cycle system comprising: a refrigerant circuit having a compressor, in which a refrigerant is circulated by the compressor; a heat medium circuit having a heat source side pump and a load side pump, in which a heat medium is circulated by the heat source side pump and the load side pump; a heat exchanger that exchanges heat between the refrigerant and the heat medium; and a system control device that controls the heat source side pump, wherein the heat medium circuit has a load device provided downstream of the heat exchanger and a free bypass piping that bypasses the load device, the heat source side pump pressure-feeds the heat medium to the heat exchanger, and the load side pump pressure-feeds the heat medium to the load device, A first detection unit provided in the heat medium circuit and configured to detect a pressure difference before and after the heat exchanger; A second detection unit is provided on a load side of the heat medium circuit and detects a load side flow rate of the heat medium, The system control device includes: a pump head of the heat source side pump is calculated from the pressure difference detected by the first detection unit and a rotation speed of the heat source side pump, and a load side flow rate of the heat medium flowing on the load side of the heat medium circuit is calculated based on the pressure difference and the pump head; The difference between the calculated value of the load side flow rate and the actual value of the load side flow rate detected by the second detection unit is compared with a pre-stored difference value to determine the scale buildup state of the heat exchanger. Refrigeration cycle system.

4. A refrigeration cycle system comprising: a refrigerant circuit having a compressor, in which a refrigerant is circulated by the compressor; a heat medium circuit having a heat source side pump and a load side pump, in which a heat medium is circulated by the heat source side pump and the load side pump; a heat exchanger that exchanges heat between the refrigerant and the heat medium; and a system control device that controls the heat source side pump, wherein the heat medium circuit has a load device provided downstream of the heat exchanger and a free bypass piping that bypasses the load device, the heat source side pump pressure-feeds the heat medium to the heat exchanger, and the load side pump pressure-feeds the heat medium to the load device, A first detection unit provided in the heat medium circuit and configured to detect a pressure difference before and after the heat exchanger; a second detection unit provided in the heat medium circuit and detecting a pump pressure difference between before and after the heat source pump; The system control device includes: a head of the heat source side pump is obtained from the differential pressure detected by the first detection unit and a rotation speed of the heat source side pump, a load side flow rate of the heat medium flowing on the load side of the heat medium circuit is calculated based on the differential pressure and the head to obtain a first calculated value, and a load side flow rate of the heat medium flowing on the load side of the heat medium circuit is calculated based on the differential pressure detected by the first detection unit and the pump differential pressure detected by the second detection unit to obtain a second calculated value; The difference between the first calculated value and the second calculated value of the load side flow rate is compared with a previously stored difference value to determine the scale buildup state of the heat exchanger. Refrigeration cycle system.

5. The system control device stores the difference calculated in an initial state in which the heat exchanger has no scale, as the pre-stored difference value. The refrigeration cycle system according to any one of claims 1 to 4.

6. a plurality of refrigeration cycle devices each having the refrigerant circuit, the heat source side pump, and the heat exchanger; The heat medium circuit has a plurality of heat source side branch pipes in which the heat source side pumps and the heat exchangers of the refrigeration cycle devices are provided, and the plurality of heat source side branch pipes are connected in parallel to each other and connected to a load side. The refrigeration cycle system according to any one of claims 1 to 4.

7. A notification unit having a display or a speaker is provided, The system control device is configured to notify the fact that the scale is deposited by the notification unit when the difference deviates from the pre-stored difference value by a certain amount or more. The refrigeration cycle system according to any one of claims 1 to 4.

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