Control device, refrigeration cycle device provided with same, refrigeration cycle system provided with same, control method, and control program

Abstract

Provided are: a control device capable of ascertaining the flow rate of a fluid to be heat-exchanged while suppressing an increase in cost of the refrigeration cycle device; a refrigeration cycle device provided with the same; a refrigeration cycle system provided with the same; a control method; and a control program. A control device (5) of a refrigeration cycle device (2) comprises: a temperature acquisition unit (51) that acquires the temperature of a fluid to be heat-exchanged; a pressure acquisition unit (51) that acquires a plurality of pressures of the fluid to be heat-exchanged flowing through a heat exchanger (HE); a setting information acquisition unit (52) that acquires the type and concentration of the fluid to be heat-exchanged; a physical property value calculation unit (53) that calculates the density and the kinematic viscosity of the fluid to be heat-exchanged; and a flow rate calculation unit (54) that calculates the differential pressure of each pressure of the fluid to be heat-exchanged and calculates the flow rate of the fluid to be heat-exchanged by using the density, kinematic viscosity, and differential pressure of the fluid to be heat-exchanged with respect to a flow rate calculation formula that includes the density, kinematic viscosity, and differential pressure as parameters.

Description

Control device, refrigeration cycle device equipped with the same, refrigeration cycle system equipped with the same, control method, and control program

[0001] The present disclosure relates to a control device, a refrigeration cycle device including the same, a refrigeration cycle system including the same, a control method, and a control program.

[0002] In a conventional refrigeration cycle device that supplies a heat exchange fluid (e.g., brine) cooled to a desired temperature, the flow rate of the heat exchange fluid has been measured directly using a flow meter, etc. In addition, such a refrigeration cycle device detects abnormalities in the flow rate of the heat exchange fluid caused by freezing, etc., using the directly measured flow rate of the heat exchange fluid.

[0003] Patent document 1 discloses a method in which, in order to reduce costs, a refrigeration cycle device does not use a flow meter, but instead detects the pressure and temperature of the refrigerant in the refrigeration cycle device and the temperature of the heat exchange fluid, and calculates the flow rate of the heat exchange fluid based on the detection results.

[0004] Furthermore, Patent Document 2 discloses a technique for calculating the absolute flow rate of a fluid to be cooled based on the low pressure of the refrigerant drawn into a compressor provided in a refrigeration cycle device, the temperature of the refrigerant drawn into the compressor, the operating frequency of the compressor, the temperature of the refrigerant to be cooled flowing into an evaporator, and the temperature of the refrigerant to be cooled flowing out of the evaporator. Thus, Patent Document 2 discloses a technique for using physical quantities related to the operation of the compressor when calculating the flow rate of the fluid to be cooled in this refrigeration cycle device.

[0005] Patent No. 5289475 Patent No. 5058324

[0006] However, the method of using a pressure gauge instead of a flow meter can only be applied when a specific heat exchange fluid is used that is set by the user at the start of operation of the refrigeration cycle device, and cannot be applied when various heat exchange fluids are used by different users. Therefore, the settable range of the heat exchange fluid to be used is limited. Therefore, when measuring the flow rate of the heat exchange fluid using a pressure gauge, it is desired to expand the settable range of the heat exchange fluid to be used.

[0007] In addition, in conventional methods, the pressure and temperature of the refrigerant drawn into the compressor are used to calculate the flow rate of the heat-exchanged fluid. In other words, in conventional methods, when only the fluid circuit on the heat-exchanged fluid side is operating, for example, when the refrigeration cycle side is not operating as a refrigerant but only a pump, the flow rate of the heat-exchanged fluid cannot be calculated. Therefore, in order to calculate the flow rate of the heat-exchanged fluid, it is necessary to operate the refrigeration cycle on the refrigerant side, which includes the compressor. Therefore, there is room for improvement in the efficiency of the operation of the refrigeration cycle device.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide a control device that can grasp the flow rate of the heat exchange fluid while suppressing an increase in the cost of the refrigeration cycle device, a refrigeration cycle device equipped with the same, a refrigeration cycle system equipped with the same, a control method, and a control program.

[0009] A control device according to some embodiments of the present disclosure is a control device for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, and includes: a temperature acquisition unit that acquires the temperature of the heat-exchanged fluid; a pressure acquisition unit that acquires the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition unit that acquires setting information on the type and concentration of the heat-exchanged fluid; a physical property value calculation unit that calculates the density and kinetic viscosity of the heat-exchanged fluid using the temperature acquired by the temperature acquisition unit and the setting information acquired by the setting information acquisition unit; and a flow rate calculation unit that calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property value calculation unit in a flow rate calculation formula that includes density, kinetic viscosity, and differential pressure as parameters.

[0010] A refrigeration cycle device according to some embodiments of the present disclosure includes the above-described control device.

[0011] A refrigeration cycle system according to some embodiments of the present disclosure includes the above-described refrigeration cycle device and a fluid circuit through which the heat exchange fluid circulates.

[0012] A control method according to some embodiments of the present disclosure is a control method for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, and includes a temperature acquisition process for acquiring the temperature of the heat-exchanged fluid; a pressure acquisition process for acquiring the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition process for acquiring setting information on the type and concentration of the heat-exchanged fluid; a physical property calculation process for calculating the density and kinetic viscosity of the heat-exchanged fluid using the temperature acquired in the temperature acquisition process and the setting information acquired in the setting information acquisition process; and a flow rate calculation process for calculating the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculating the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated in the physical property calculation process in a flow rate calculation formula including density, kinetic viscosity, and differential pressure as parameters.

[0013] A control program according to some embodiments of the present disclosure is a control program for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, the control program including a temperature acquisition process for acquiring a temperature of the heat-exchanged fluid; a pressure acquisition process for acquiring a pressure of the heat-exchanged fluid flowing into the heat exchanger and a pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition process for acquiring setting information on the type and concentration of the heat-exchanged fluid; and a temperature acquisition process for acquiring a temperature acquired by the temperature acquisition process. The computer is caused to execute a physical property calculation process that calculates the density and kinetic viscosity of the heat-exchanged fluid using the setting information acquired by the setting information acquisition process, and a flow rate calculation process that calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property calculation process in a flow rate calculation formula that includes density, kinetic viscosity, and differential pressure as parameters.

[0014] According to the present disclosure, it is possible to obtain the flow rate of a heat exchange fluid at low cost, regardless of the type or concentration of the heat exchange fluid.

[0015] 1 is a diagram schematically illustrating the configuration of a refrigeration cycle apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating an example of the hardware configuration of a control device of the refrigeration cycle apparatus of FIG. 1. FIG. 3 is a flowchart illustrating an example of a procedure for flow rate calculation processing of a heat-exchanged fluid in a refrigeration cycle apparatus according to an embodiment of the present disclosure. FIG. 4 is a graph showing actual measurement results of flow rate-pressure loss characteristics of a heat-exchanged fluid. FIG. 5 is an example of a data sheet from a manufacturer of the heat-exchanged fluid. FIG. 6 is a graph showing an approximation formula for the temperature and density of the heat-exchanged fluid. FIG. 7 is a graph showing an approximation formula for the temperature and viscosity of the heat-exchanged fluid. FIG. 8 is a dimensionless characteristic graph illustrating the relationship between the Reynolds number of a heat-exchanged fluid and pressure loss / dynamic pressure. FIG. 9 is a diagram schematically illustrating the configuration of a refrigeration cycle apparatus according to an embodiment of the present disclosure. FIG. 10 is a graph illustrating an example of the specific gravity versus concentration of a heat-exchanged fluid. FIG. 11 is a graph illustrating an example of the freezing temperature versus concentration of a heat-exchanged fluid.

[0016] Hereinafter, an embodiment of a control device, a refrigeration cycle device including the same, a refrigeration cycle system including the same, a control method, and a control program according to the present disclosure will be described with reference to the drawings.

[0017] (Configuration of Refrigeration Cycle System) Fig. 1 is a diagram schematically illustrating the configuration of a refrigeration cycle system 1 according to an embodiment of the present disclosure. As shown in Fig. 1, the refrigeration cycle system 1 includes a fluid circuit 4 and a refrigeration cycle device 2.

[0018] (Fluid Circuit) The fluid circuit 4 is a fluid circuit through which a heat-exchanged fluid circulates. As described below, the heat-exchanged fluid exchanges heat with the refrigerant circulating through the refrigerant circuit 3 in a heat exchanger HE, and supplies the heat-exchanged fluid at a desired temperature to an equipment load 42. The fluid circuit 4 is provided with, for example, a pump 41, pressure sensors P1 and P2, and temperature sensors (temperature measurement units) T1 and T2. The heat-exchanged fluid is a fluid such as water, and may be simple water or brine containing an additive that lowers the freezing point. In this embodiment, the heat-exchanged fluid is brine, and examples of such brines may include ethylene glycol, Nybrine Z1, Nybrine NFP, Shobrine Blue, and Shobrine PFP.

[0019] The pump 41 delivers the heat exchange fluid so that the heat exchange fluid circulates through the fluid circuit 4. Here, the means for delivering the heat exchange fluid is not limited to a pump, and other types of delivery means may be used as long as they perform a similar function.

[0020] The pressure sensors P1 and P2 are provided, for example, at the inlet and outlet of the heat exchanger HE in the fluid circuit 4. The pressure sensor P1 measures the pressure of the heat-exchanged fluid flowing into the heat exchanger HE. The pressure sensor P2 measures the pressure of the heat-exchanged fluid flowing out of the heat exchanger HE. The measured pressures are sent to the control device 5 and used for calculating the flow rate of the heat-exchanged fluid, which will be described later. Instead of the pressure sensors P1 and P2, a differential pressure gauge may be used that measures the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger HE and the pressure of the heat-exchanged fluid flowing out of the heat exchanger HE.

[0021] The temperature sensors T1 and T2 are provided, for example, at the inlet and outlet of the heat exchanger HE in the fluid circuit 4. The temperature sensor (first temperature measurement unit) T1 measures the temperature of the heat-exchanged fluid flowing into the heat exchanger HE. The temperature sensor (second temperature measurement unit) T2 measures the temperature of the heat-exchanged fluid flowing out of the heat exchanger HE. The measured temperatures are sent to the control device 5 and used for calculating the flow rate of the heat-exchanged fluid, which will be described later. When the temperature difference between the inlet and outlet of the heat exchanger HE is small, only the temperature sensor T1, which measures the temperature of the heat-exchanged fluid flowing into the heat exchanger HE, may be provided.

[0022] (Refrigeration Cycle Apparatus) The refrigeration cycle apparatus 2 includes a refrigerant circuit 3, a control device 5, a storage unit 6, and a notification unit 7. Each component will be described in detail below.

[0023] (Refrigerant Circuit) First, the refrigerant circuit 3 is a fluid circuit through which a refrigerant circulates, and includes a compressor 31, a heat exchanger 32, a pressure reducer 33, and a heat exchanger HE. The refrigerant circulating through the refrigerant circuit 3 may be, for example, an HFC refrigerant such as R410A, R407C, or R404A, an HCFC refrigerant such as R22 or R134a, or a natural refrigerant such as hydrocarbon or helium. The refrigerant circulating through the refrigerant circuit 3 is not limited to these, and may be any other refrigerant that has a similar refrigerant function.

[0024] The compressor 31 compresses the refrigerant circulating through the refrigerant circuit 3. The compressor 31 is a compressor whose operating capacity is variable, and is configured, for example, as a positive displacement compressor driven by a motor controlled by an inverter. The compressor 31 may be configured such that two or more compressors are connected in parallel or in series.

[0025] Specifically, the heat exchanger 32 is a condenser that exchanges heat between a refrigerant and a heat exchange medium. The heat exchanger 32 is, for example, a fin-and-tube heat exchanger that includes a heat transfer tube and a number of fins. The heat exchange medium is, for example, a fluid such as air, and is supplied to the heat exchanger 32 by a delivery means such as a fan.

[0026] The pressure reducer 33 adjusts the flow rate of the refrigerant flowing through the refrigerant circuit 3. As the pressure reducer 33, an electronic expansion valve capable of adjusting the aperture opening degree by a stepping motor (not shown), a mechanical expansion valve employing a diaphragm in the pressure receiving portion, a capillary tube, or the like may be used.

[0027] The heat exchanger HE is a heat exchanger that exchanges heat between the refrigerant circulating through the refrigerant circuit 3, whose pressure has been reduced by the pressure reducer 33, and the heat-exchanged fluid circulating through the fluid circuit 4. Specifically, the heat exchanger HE is an evaporator, and a fin-and-tube heat exchanger, for example, is used. The heat exchanger HE is a component of both the refrigerant circuit 3 and the fluid circuit 4.

[0028] (Control Device) The control device 5 calculates the flow rate of the heat exchange fluid based on the pressures measured by the pressure sensors P1, P2, the temperatures measured by the temperature sensors T1, T2, and setting information on the type and concentration of the heat exchange fluid input by the user, and controls the drive of the compressor 31 and pressure reducer 33 provided in the refrigerant circuit 3 and the pump 41 provided in the fluid circuit 4. The control device 5 also includes an operating state information acquisition unit 51, a setting information acquisition unit 52, a physical property value calculation unit 53, a flow rate calculation unit 54, a capacity calculation unit 55, an abnormality determination unit 56, an abnormality processing unit 57, an equipment drive control unit 58, and a memory unit 6.

[0029] Here, Fig. 2 is a schematic diagram showing an example of the hardware configuration of the control device 5 of the refrigeration cycle apparatus 2 of Fig. 1. As shown in Fig. 2, the control device 5 has a computer (computer system) and includes, for example, a CPU 5a, an auxiliary storage device (ROM) 5b for storing programs executed by the CPU 5a and data referenced by these programs, a main storage device (RAM) 5c that functions as a work area when each program is executed, a communication interface 5d for connecting to a network, and an input / output unit 5e that accepts input from external devices and outputs control commands to external devices that can communicate with the control device 5. These units are connected, for example, via a bus 5f. Examples of the auxiliary storage device 5b include a magnetic disk, a magneto-optical disk, and a semiconductor memory.

[0030] A series of processes for realizing the various functions described below is stored in the auxiliary storage device 5b in the form of a program, for example, and the CPU 5a reads this program into the main storage device 5c and executes information processing and arithmetic operations to realize the various functions. The program may be pre-installed in the auxiliary storage device 5b, provided in a state stored in another computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0031] 1 , the operating state information acquisition unit (pressure acquisition unit, temperature acquisition unit) 51 acquires the pressure of the heat-exchanged fluid using pressure sensors P1 and P2 and the temperature of the heat-exchanged fluid using temperature sensors T1 and T2, and outputs the acquired values ​​to the physical property value calculation unit 53 and the flow rate calculation unit 54. In the following description, the operating state information acquisition unit 51 is assumed to be capable of acquiring physical quantities such as the temperature of the refrigerant circulating through the refrigerant circuit 3 and the temperature, pressure, and differential pressure of the heat-exchanged fluid circulating through the fluid circuit 4. However, this is not limiting, and the operating state information acquisition unit 51 may appropriately include a temperature acquisition unit that acquires the temperature of the refrigerant circulating through the refrigerant circuit 3 and / or the temperature of the heat-exchanged fluid circulating through the fluid circuit 4, a pressure acquisition unit that acquires the temperature of the refrigerant circulating through the refrigerant circuit 3 and / or the pressure of the heat-exchanged fluid circulating through the fluid circuit 4, and a differential pressure acquisition unit that acquires the temperature of the refrigerant circulating through the refrigerant circuit 3 and / or the pressure of the heat-exchanged fluid circulating through the fluid circuit 4.

[0032] The setting information acquisition unit 52 acquires setting information about the type and concentration of the heat-exchange fluid. The setting information about the type and concentration of the heat-exchange fluid is set by a user, for example, via a user interface (not shown). The setting information about the type and concentration of the heat-exchange fluid set by the user is used to calculate the physical property values ​​of the heat-exchange fluid. Therefore, the setting information acquisition unit 52 outputs the setting information about the type and concentration of the heat-exchange fluid to the physical property value calculation unit 53.

[0033] The physical property value calculation unit 53 calculates the density and kinetic viscosity of the heat-exchange fluid using the temperature of the heat-exchange fluid received from the operating state information acquisition unit 51 and the setting information on the type and concentration of the heat-exchange fluid received from the setting information acquisition unit 52. The physical property value calculation unit 53 then outputs the calculated density and kinetic viscosity of the heat-exchange fluid to the flow rate calculation unit 54 and the capacity calculation unit 55, respectively.

[0034] Furthermore, in calculating the density and kinematic viscosity of the heat-exchanged fluid, the physical property calculation unit 53 may use a data table and calculation formulas relating to the physical property values ​​of the heat-exchanged fluid stored in the storage unit 6, which will be described later. Furthermore, when multiple temperatures of the heat-exchanged fluid are received from the operating state information acquisition unit 51, the physical property calculation unit 53 may calculate an average temperature. The physical property values ​​calculated by the physical property calculation unit 53 are not limited to those described above, and other physical property values ​​such as specific heat may also be calculated.

[0035] The flow rate calculation unit 54 calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property calculation unit 53 in a flow rate calculation formula containing the density, kinetic viscosity, and differential pressure as parameters. The flow rate calculation unit 54 then outputs the calculated flow rate of the heat-exchanged fluid to both the capacity calculation unit 55 and the abnormality determination unit 56.

[0036] In addition, the flow rate calculation unit 54 may use an arithmetic expression for calculating the flow rate of the heat exchange fluid stored in the storage unit 6, which will be described later, in calculating the flow rate of the heat exchange fluid. Furthermore, the flow rate calculation unit 54 may output the calculation result externally by displaying it on a monitor or the like in order to notify the user of the calculated flow rate of the heat exchange fluid.

[0037] The capacity calculation unit 55 calculates the capacity of the refrigerant circuit 3, the capacity of the fluid circuit 4, and the capacity of the refrigeration cycle apparatus 2 based on the calculation results of the physical property calculation unit 53 and the flow rate calculation unit 54. For example, the capacity calculation unit 55 calculates the heat exchange amount of the refrigerant and the heat exchange fluid. Then, based on the calculation results, the capacity calculation unit 55 outputs the calculation results externally by displaying on a monitor or the like to notify the user of the current capacity of the refrigeration cycle apparatus 2.

[0038] The abnormality determination unit 56 determines whether or not there is an abnormality in the flow rate of the heat exchange fluid based on the calculation result of the flow rate calculation unit 54. The abnormality determination unit 56 also outputs the abnormality determination result to the abnormality processing unit 57. When the abnormality determination unit 56 determines that there is an abnormality in the flow rate, it transmits a signal indicating that there is an abnormality to the notification unit 7. The notification unit 7 then notifies the user of the refrigeration cycle apparatus 2 that an abnormality has occurred in the flow rate. The abnormality determination unit 56 may be configured to perform abnormality determination not only on the flow rate of the heat exchange fluid, but also on other physical property values ​​of the heat exchange fluid, such as the concentration of the heat exchange fluid.

[0039] When the abnormality processing unit 57 receives a determination result indicating an abnormality in the flow rate from the abnormality determination unit 56, it outputs a command to the device drive control unit 58 to cause each device included in the refrigerant circuit 3 or the fluid circuit 4 to perform a dedicated operation in the event of an abnormality. The dedicated operation may be, for example, a preset operation, or may be a command to perform an emergency stop.

[0040] The device drive control unit 58 uses the calculation result of the flow rate calculation unit 54 as one of the parameters to control the drive of each device, such as the compressor 31, the pressure reducer 33, and the pump 41. For example, the device drive control unit 58 controls the rotation speed of the compressor 31, the valve opening if the pressure reducer 33 is a valve, the rotation speed of the pump 41, etc., thereby controlling the pressure, temperature, flow rate, etc. of the refrigerant circulating through the refrigerant circuit 3 or the heat exchange fluid circulating through the fluid circuit 4. Furthermore, when the device drive control unit 58 receives a command from the abnormality processing unit 57 to perform an emergency stop when an abnormality occurs, the device drive control unit 58 may perform an emergency stop of each device provided in the refrigerant circuit 3 and the fluid circuit 4 based on the command.

[0041] (Memory Unit) The memory unit 6 is composed of a memory device such as a semiconductor memory or a hard disk drive. The memory unit 6 stores various calculation formulas used by the physical property calculation unit 53 to calculate physical property values ​​such as density and kinematic viscosity, and a flow rate calculation formula used by the flow rate calculation unit 54 to calculate the flow rate of the heat-exchanged fluid. The memory unit 6 also stores a plurality of data tables for obtaining various physical property values ​​in which temperature and differential pressure are associated for each combination of the type and concentration of the heat-exchanged fluid. The data tables include, for example, a density table showing the relationship between density and temperature, type, and concentration of the heat-exchanged fluid; a viscosity table showing the relationship between viscosity and temperature, type, and concentration of the heat-exchanged fluid; a specific heat table showing the relationship between specific heat and temperature, type, and concentration of the heat-exchanged fluid; a specific gravity table showing the relationship between specific gravity and concentration of the heat-exchanged fluid; and a freezing temperature table showing the relationship between freezing temperature and concentration of the heat-exchanged fluid. The calculation formulas used by the physical property calculation unit 53 and the flow rate calculation formula used by the flow rate calculation unit 54 are derived using at least one of the data tables. The storage unit 6 may also store specifications such as dimensions of the pipes through which the heat exchange fluid flows. The storage unit 6 can communicate with the control device 5, and each calculation unit included in the control device 5 may use each table stored in the storage unit 6 when performing calculations. The storage unit 6 is configured with a memory device such as a semiconductor memory or a hard disk drive, and is not limited to the configuration provided in the control device 5. The storage unit 6 may be a cloud service, for example, online storage, as long as it is accessible by the control device 5.

[0042] (Notification Unit) The notification unit 7 is a display screen such as an LED (Light Emitting Diode) or a CRT (Cathode Ray Tube) or a liquid crystal screen, and outputs information on the screen. If the judgment result is a flow rate abnormality, the notification unit 7 displays and outputs the flow rate abnormality in response to an instruction from the abnormality judgment unit 56. Furthermore, the notification unit 7 may be provided with an audio output unit such as a speaker, and may output information as an audio alarm instead of or in addition to the display output on the screen. Furthermore, the notification unit 7 may have a communication line and may execute communication data output to a remote location.

[0043] (Regarding Flow Rate Calculation) The following describes in detail the contents of the calculations performed by the storage unit 6, the physical property value calculation unit 53, and the flow rate calculation unit 54. First, the physical property value calculation unit 53 calculates the density ρ of the heat exchange fluid according to the following formula (1) stored in the storage unit 6, using the temperature of the heat exchange fluid obtained via the operating state information acquisition unit 51 and the setting information on the type and concentration of the heat exchange fluid received from the setting information acquisition unit 52.

[0044]

[0045] In equation (1), ρ is the density of the heat-exchanged fluid, Tin is the temperature of the heat-exchanged fluid flowing into the heat exchanger HE, and Tout is the temperature of the heat-exchanged fluid flowing out of the heat exchanger HE. Here, ρ(t) is an approximation formula for the density of the heat-exchanged fluid based on a previously measured value, and t is the temperature of the heat-exchanged fluid. The approximation formula ρ(t) will be described in detail later.

[0046] In addition, the physical property value calculation unit 53 calculates the viscosity μ of the heat exchange fluid using the temperature of the heat exchange fluid obtained via the operating state information acquisition unit 51 and the setting information of the type and concentration of the heat exchange fluid received from the setting information acquisition unit 52, using the following formula (2) stored in the memory unit 6.

[0047]

[0048] In equation (2), μ is the viscosity of the heat-exchanged fluid, Tin is the temperature of the heat-exchanged fluid flowing into the heat exchanger HE, and Tout is the temperature of the heat-exchanged fluid flowing out of the heat exchanger HE. Here, μ(t) is an approximation formula for the viscosity of the heat-exchanged fluid based on a previously measured value, and t is the temperature of the heat-exchanged fluid. The approximation formula μ(t) will be described in detail later.

[0049] The physical property calculation unit 53 further calculates the kinetic viscosity ν of the heat exchange fluid using the density ρ and viscosity μ obtained by equations (1) and (2) according to the following equation (3) stored in the memory unit 6.

[0050]

[0051] In this way, the physical property value calculation unit 53 calculates the density ρ, viscosity μ, and kinematic viscosity ν, which are the physical property values ​​of the heat exchange fluid, using each calculation formula stored in the storage unit 6. In addition, the physical property value calculation unit 53 outputs the density ρ and kinematic viscosity ν to the flow rate calculation unit 54.

[0052] Next, the flow rate calculation unit 54 calculates the flow rate Q of the heat exchange fluid using the density and kinetic viscosity of the heat exchange fluid calculated by the physical property calculation unit 53, and the differential pressure calculated from the pressure of the heat exchange fluid flowing into the heat exchanger and the pressure of the heat exchange fluid flowing out of the heat exchanger, using the following formula (4) stored in the memory unit 6.

[0053]

[0054] In equation (4), Q is the flow rate of the heat exchange fluid, Δp is the differential pressure, ρ is the density of the heat exchange fluid, ν is the kinematic viscosity of the heat exchange fluid, and the predetermined values ​​α, β, and γ are predetermined values ​​obtained in advance by actual measurement. Here, the specific details of the means for setting the predetermined values ​​α, β, and γ will be described later.

[0055] As described above, the physical property value calculation unit 53 calculates the density and kinetic viscosity of the heat-exchanged fluid using the temperatures measured by the temperature sensors T1, T2 and the setting information (type and concentration of the heat-exchanged fluid) acquired by the setting information acquisition unit 52. Furthermore, the flow rate calculation unit 54 calculates the flow rate of the heat-exchanged fluid by using the density and kinetic viscosity of the heat-exchanged fluid calculated by the physical property value calculation unit 53 and the differential pressure calculated from the pressure of the heat-exchanged fluid flowing into the heat exchanger HE and the pressure of the heat-exchanged fluid flowing out of the heat exchanger HE in a flow rate calculation formula including the density, kinetic viscosity, and differential pressure as parameters.

[0056] According to this method, the flow rate of the heat exchange fluid can be determined without providing a flow meter, i.e., while suppressing an increase in the cost of the refrigeration cycle apparatus 2. The flow rate of the heat exchange fluid can be accurately calculated without being bound by the type and concentration of the heat exchange fluid set arbitrarily by the user. Furthermore, since the flow rate of the heat exchange fluid can be determined based on the temperature, differential pressure, type, and concentration of the heat exchange fluid flowing through the fluid circuit 4, the flow rate of the heat exchange fluid can be determined even when the refrigerant circuit 3 on the refrigerant side is not operated.

[0057] (Flow Rate Calculation in Refrigeration Cycle Apparatus) Next, a description will be given of an example of a flow rate calculation process of the heat exchange fluid in the refrigeration cycle apparatus 2. Fig. 3 is a flowchart showing an example of a procedure of a flow rate calculation process of the heat exchange fluid in the refrigeration cycle apparatus 2 according to an embodiment of the present disclosure.

[0058] First, as a preliminary preparation for the flow rate calculation process of the heat exchange fluid, predetermined values ​​α, β, and γ are obtained by measuring the actual fluid (S101). Next, the user sets the type and concentration of the heat exchange fluid to be used in the refrigeration cycle device 2 (S102).

[0059] Next, the operating state information acquiring unit 51 acquires the pressures measured by the pressure sensors P1 and P2, and further acquires the temperatures measured by the temperature sensors T1 and T2 (S103).

[0060] Next, the flow rate calculation unit 54 calculates the pressure difference Δp between the pressure of the heat-exchanged fluid flowing into the heat exchanger HE and the pressure of the heat-exchanged fluid flowing out of the heat exchanger HE (S104). Next, the physical property calculation unit 53 calculates the density ρ from the type and concentration of the heat-exchanged fluid and the integral average of the inlet and outlet temperatures of the heat exchanger HE (S105).

[0061] Next, the physical property value calculation unit 53 calculates the viscosity μ from the type and concentration of the heat exchange fluid and the integral average of the inlet and outlet temperatures of the heat exchanger HE (S106). Next, the physical property value calculation unit 53 calculates the kinetic viscosity ν from the density ρ and viscosity μ (S107).

[0062] Finally, the flow rate calculation unit 54 calculates the flow rate Q from the differential pressure Δp, density ρ, kinematic viscosity ν, and predetermined values ​​α, β, and γ of the heat exchange fluid (S108).

[0063] As described above, by calculating the flow rate of the heat exchange fluid using the flow rate calculation unit 54, the flow rate of the heat exchange fluid can be determined without providing a flow meter, i.e., while suppressing an increase in the cost of the refrigeration cycle apparatus 2. In addition, the flow rate of the heat exchange fluid can be accurately calculated without being bound by the type and concentration of the heat exchange fluid arbitrarily set by the user. Furthermore, because the flow rate of the heat exchange fluid can be determined based on the temperature, differential pressure, type, and concentration of the heat exchange fluid flowing through the fluid circuit 4, the flow rate of the heat exchange fluid can be determined even when the refrigerant circuit 3 on the refrigerant side is not driven.

[0064] 3 may include additional steps without departing from the scope of the present disclosure. For example, after step S108, a step may be added in which the abnormality determination unit 56 determines whether or not there is an abnormality in the flow rate of the heat exchange fluid based on the calculation result of the flow rate calculation unit 54.

[0065] Also, for example, after step S108, a step may be added in which the equipment drive control unit 58 performs feedback control on the compressor 31, the pressure reducer 33, and the pump 41 based on the calculation result of the flow rate calculation unit 54. Furthermore, each process in the flow shown in Fig. 3 may be repeatedly executed at predetermined intervals while the fluid circuit 4 is in operation.

[0066] (Procedure for Derivation of Each Calculation Formula) The inventors have derived calculation formulas for calculating the density, kinematic viscosity, and flow rate of the heat exchange fluid using acquired information about the heat exchange fluid, in order to calculate the flow rate of the heat exchange fluid, as described above. The procedure for derivation of each calculation formula will be described below.

[0067] [Step (1) Measurement on Actual Machine] First, experimental measurements are carried out in advance to understand the relationship between the flow rate of the heat-exchanged fluid and each parameter. Specifically, the pump 41 of the fluid circuit 4 is operated without refrigerant operation, i.e., without operating the refrigerant circuit 3, and the flow rate of the heat-exchanged fluid and the inlet and outlet temperatures of the heat exchanger HE are measured to obtain the flow rate-pressure loss (differential pressure) characteristics of the heat-exchanged fluid. FIG. 4 is a graph showing the results of actual measurements of the flow rate-pressure loss characteristics of the heat-exchanged fluid. In FIG. 4, the horizontal axis represents the flow rate of the heat-exchanged fluid, and the vertical axis represents the differential pressure of the heat-exchanged fluid. In FIG. 4, the solid, dashed, and dashed lines represent graphs for the same type and concentration of the heat-exchanged fluid, with only the temperature of the heat-exchanged fluid being different. According to FIG. 4, the difference in flow rate between when the inlet temperature of the heat-exchanged fluid is -15°C and when it is 15°C is approximately 5 m / s. ３ For the physical property values ​​of the heat-exchange fluid, technical documents such as a data sheet from the manufacturer of the heat-exchange fluid (see, for example, FIG. 5) may be referenced.

[0068] [Step (2) Deriving Approximate Formulas for the Physical Properties of the Heat Exchanged Fluid and the Temperature Inlet and Outlet of the Heat Exchanger] Next, using technical documentation from the manufacturer of the heat exchanged fluid, approximate formulas are created for the density and viscosity of the heat exchanged fluid, with the temperature of the heat exchanged fluid as a variable. Figure 6 is a graph showing the approximate formula for density created using the temperature of the heat exchanged fluid and the technical documentation from the manufacturer of the heat exchanged fluid. In Figure 6, the horizontal axis represents the temperature of the heat exchanged fluid, and the vertical axis represents the density of the heat exchanged fluid. Figure 7 is a graph showing the approximate formula for viscosity created using the temperature of the heat exchanged fluid and the technical documentation from the manufacturer of the heat exchanged fluid. In Figure 7, the horizontal axis represents the temperature of the heat exchanged fluid, and the vertical axis represents the viscosity of the heat exchanged fluid.

[0069] As shown in Figure 6, the change in density of the heat-exchanged fluid with respect to its temperature is approximately linear. Therefore, a quadratic approximation equation can be used to obtain sufficient prediction accuracy for the change in density of the heat-exchanged fluid with respect to its temperature. Specifically, the density of the heat-exchanged fluid with respect to its temperature is calculated using the following equation (5). In equation (5), ρ(t) is a function of the density of the heat-exchanged fluid, and ρ ０ is a constant calculated when creating the approximation formula, and ρ １ , ρ ２is a coefficient calculated when the approximation formula is created, and t is the temperature of the fluid to be heat exchanged.

[0070]

[0071] As shown in Figure 7, the change in viscosity of the heat-exchanged fluid with respect to temperature is not approximately linear as in Figure 6. For this reason, the change in viscosity of the heat-exchanged fluid with respect to temperature is large, so it is expressed by a fifth-order approximation formula. The density of the heat-exchanged fluid with respect to temperature is calculated using the following formula (6). In formula (6), μ(t) is a function of the density of the heat-exchanged fluid, and μ ０ is a constant calculated when creating the approximation formula, and μ １ , μ ２ , μ ３ , μ ４ , μ ５ is a coefficient calculated when the approximation formula is created, and t is the temperature of the fluid to be heat exchanged.

[0072]

[0073] Here, when calculating physical property values ​​during actual refrigeration operation in the refrigerant circuit 3, the temperature difference between the inlet and outlet temperatures of the heat exchanger HE in the fluid circuit 4 is large, up to 10°C, so the average value of the inlet and outlet temperatures of the heat exchanger HE is used. A highly accurate integrated average value is used as a method for calculating the average value. Using this, Equation (1) for calculating the density of the heat-exchanged fluid is derived using Equation (5). Similarly, Equation (2) for calculating the density of the heat-exchanged fluid is derived using Equation (6).

[0074] [Step (3) Obtaining dimensionless characteristics] Based on the data obtained in the above step (1), the Reynolds number and pressure loss / dynamic pressure are calculated. Here, the Reynolds number Re is calculated using the following formula (7). Furthermore, the pressure loss / dynamic pressure is calculated using the following formula (8). In formulas (7) and (8), d is the inner diameter of the pipe through which the heat-exchanged fluid flows, U is the average flow velocity in the pipe through which the heat-exchanged fluid flows, and ν is the kinetic viscosity of the heat-exchanged fluid as defined in formula (3). Furthermore, when the flow rate of the heat-exchanged fluid is Q, the average flow velocity in the pipe is calculated as U=4Q / πd ２ It is calculated by:

[0075]

[0076]

[0077] A dimensionless characteristic graph is then created based on the calculated relationship between the Reynolds number and the pressure loss / dynamic pressure. Figure 8 is a dimensionless characteristic graph illustrating the relationship between the Reynolds number of the heat exchange fluid and the pressure loss / dynamic pressure. In Figure 8, the horizontal axis represents the Reynolds number, and the vertical axis represents the pressure loss / dynamic pressure. By creating a dimensionless characteristic graph in this way, conditions with different temperatures of the heat exchange fluid can be displayed on the same scale. Furthermore, based on the dimensionless characteristic graph, an approximate equation for the Reynolds number and the pressure loss / dynamic pressure is created using power approximation.

[0078] [Step (4) Deriving the Flow Rate Calculation Formula for the Heat Exchange Fluid (Formula (4))] Next, the approximate formula for the Reynolds number and pressure loss / dynamic pressure created in step (3) is expressed as the following formula (9).

[0079]

[0080] Substituting Equation (7) and the mean flow velocity U in the pipe into Equation (9) and rearranging the equation, we obtain the following Equation (10): a and n are constants derived from a power approximation of the Reynolds number and the pressure loss / dynamic pressure.

[0081]

[0082] From equation (10), a, d, and n are each constant, so by rearranging equation (10), the predetermined value α=(π / 4)(2 / a) １／（ｎ＋２） d （ｎ+４／ｎ+２） , β=-n, γ=1 / (n+2), the equation can be transformed into the above-mentioned formula (4). Through the above steps, the calculation formulas for calculating the density and viscosity used by the physical property calculation unit 53 and the flow rate calculation formula used by the flow rate calculation unit 54 are derived. Furthermore, the inventors have confirmed that by using the formula (4) derived in this way, it is possible to calculate the flow rate of the heat exchange fluid that is close to the actually measured value.

[0083] As described above, in the refrigeration cycle apparatus 2 of the present disclosure, the flow rate calculation unit 54 calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger HE and the pressure of the heat-exchanged fluid flowing out of the heat exchanger HE, and calculates the flow rate of the heat-exchanged fluid by using the density, kinematic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property calculation unit 53 in a flow rate calculation formula including the density, kinematic viscosity, and differential pressure as parameters. This makes it possible to determine the flow rate of the heat-exchanged fluid without providing a flow meter, i.e., while suppressing an increase in the cost of the refrigeration cycle apparatus 2. Furthermore, because the flow rate of the heat-exchanged fluid can be determined based on the temperature, differential pressure, type, and concentration of the heat-exchanged fluid flowing through the fluid circuit 4, the flow rate of the heat-exchanged fluid can be determined even when the refrigerant circuit 3 on the refrigerant side is not operated.

[0084] The flow rate calculation formula is derived from an approximation formula showing the relationship between the Reynolds number of the heat-exchanged fluid and the pressure loss / dynamic pressure, which is derived using multiple data sets in which the temperature and differential pressure are associated for each combination of the type and concentration of the heat-exchanged fluid. In other words, the flow rate of the heat-exchanged fluid is calculated using a predetermined, dimensionless calculation formula. This allows the flow rate of the heat-exchanged fluid to be accurately calculated, regardless of the type or concentration of the heat-exchanged fluid that the user arbitrarily sets.

[0085] Furthermore, the flow rate calculation of the heat exchange fluid according to the present disclosure can reduce the number of data points acquired at the timing of the flow rate calculation. For example, if a differential pressure gauge measuring the differential pressure between the inlet and outlet of the heat exchanger HE is provided in the fluid circuit 4 instead of the pressure sensors P1 and P2, the number of data points acquired during the flow rate calculation is two: the differential pressure measured by the differential pressure gauge and the inlet temperature of the heat exchanger HE. Even if a differential pressure gauge is not provided and temperatures at the inlet and outlet of the heat exchanger HE are measured, four data points are acquired: the pressures at the inlet and outlet of the heat exchanger HE and the temperatures at the inlet and outlet of the heat exchanger HE. Thus, compared to conventional methods that acquire the pressure and temperature of the refrigerant side, the rotation speed of the compressor 31 provided in the refrigerant circuit 3, the flow rate calculation according to the present disclosure requires fewer data points, thereby minimizing the strain on software capacity during the calculation process. Furthermore, the fewer data points facilitates program creation and reduces the occurrence of design errors.

[0086] Furthermore, the flow rate of the heat exchange fluid according to the present disclosure can be calculated by acquiring at least two pieces of data. Here, for example, if the failure probability of each of the multiple data acquisition units (e.g., sensors) is equal to n, the failure probability when there are two data acquisition units is 1-(1-n). ２ Similarly, the failure probability when there are two data acquisition units is 1-(1-n) ６ In this way, regardless of the value of n, having fewer data acquisition points can reduce the probability of insufficient data for flow rate calculation. In other words, having fewer data acquisition points can reduce the probability of flow rate calculation becoming impossible.

[0087] (Another embodiment: detection of change in concentration of heat-exchanged fluid) The calculation of the flow rate of the heat-exchanged fluid has been described with respect to the refrigeration cycle apparatus 2 in the present disclosure. Below, a method for calculating the capacity of the refrigeration cycle apparatus 2 and the change in concentration of the heat-exchanged fluid using the above-mentioned configuration will be described. FIG. 9 is a diagram schematically showing the configuration of a refrigeration cycle system 10 according to this embodiment. In the configuration diagram of FIG. 1, pressure sensors P1, P2 and temperature sensors T1, T2 are provided only in the fluid circuit 4. However, in this embodiment, as shown in FIG. 9, pressure sensors P3, P4 and temperature sensors T3, T4 are also provided in the refrigerant circuit 3, similar to the fluid circuit 4.

[0088] The pressure sensors P3 and P4 are provided, for example, at the inlet and outlet, respectively, of the compressor 31 in the refrigerant circuit 3. The pressure sensor P3 measures the pressure of the refrigerant flowing into the compressor. The pressure sensor P4 measures the pressure of the refrigerant flowing out of the compressor 31. The measured pressures are sent to the control device 5 and used for calculating the heat exchange amount of the refrigerant circuit 3, which will be described later.

[0089] The temperature sensors T3 and T4 are provided, for example, at the inlet and outlet, respectively, of the heat exchanger HE in the refrigerant circuit 3. The temperature sensor T3 measures the temperature of the heat-exchanged fluid flowing into the heat exchanger HE. The temperature sensor T4 measures the temperature of the heat-exchanged fluid flowing out of the heat exchanger HE. The measured temperatures are sent to the control device 5 and used in calculating the heat exchange amount of the refrigerant circuit 3, which will be described later.

[0090] Furthermore, the control device 5 in this embodiment calculates the enthalpies of the inlet and outlet of the heat exchanger HE using the operating state information received from the operating state information acquisition unit 51, specifically, the refrigerant pressure measured by the pressure sensor P3 and the refrigerant temperatures measured by the temperature sensors T3 and T4, and further calculates the enthalpy difference between the inlet and outlet of the heat exchanger HE. The pressure used to calculate the enthalpy difference between the inlet and outlet of the heat exchanger HE may be a value that takes into account the pressure loss generated by the heat exchanger HE relative to the measurement result measured by the pressure sensor P3. While the present disclosure describes an example in which the enthalpies are calculated using the pressure measured by the pressure sensor P3 provided on the inlet side of the compressor 31, this is not limiting. More preferably, the enthalpies may be calculated using the pressure measured by a pressure sensor provided on the inlet side of the heat exchanger HE. The calculation of the enthalpy difference between the inlet and outlet of the heat exchanger HE may be performed using any known method, and detailed description thereof will be omitted. Furthermore, the abnormality determination unit 56 in this embodiment is capable of two-way communication with the capacity calculation unit 55, and has a function of detecting a change in concentration of the heat exchange fluid using the calculation results of the capacity calculation unit 55. Furthermore, the flow rate calculation unit 54 in this embodiment is capable of calculating the flow rate of the refrigerant circulating through the refrigerant circuit 3, and the capacity calculation unit 55 is capable of calculating the capacity of the refrigerant circuit 3. The other configurations are the same as those shown in FIG.

[0091] First, when heat is exchanged between the refrigerant and the heat-exchanged fluid via the heat exchanger HE, the heat exchange amount in the heat exchanger HE changes depending on the operating state of the refrigeration cycle apparatus 2. The heat exchange amount of the refrigerant in the heat exchanger HE and the heat exchange amount of the heat-exchanged fluid in the heat exchanger HE are equal if the concentration of the heat-exchanged fluid is normal. Therefore, if the heat exchange amount in the refrigerant circuit 3 and the heat exchange amount in the fluid circuit 4 are not equal, it can be assumed that the concentration of the heat-exchanged fluid has changed.

[0092] To check for a change in the concentration of the heat-exchanged fluid, the capacity calculation unit 55 first calculates a first heat exchange amount Qr in the refrigerant circuit 3 and a second heat exchange amount Qb in the fluid circuit 4 using the calculation results of the state quantity calculation unit 60, the physical property calculation unit 53, and the flow rate calculation unit 54 (described later). The abnormality determination unit 56 then compares the calculated heat exchange amounts to detect a change in the concentration of the heat-exchanged fluid based on the difference between the first and second heat exchange amounts. In this manner, in this embodiment, the abnormality determination unit 56 functions as a concentration change detection unit that detects a change in the concentration of the heat-exchanged fluid. This example is not limiting, and the control device 5 may also include a concentration change detection unit independent of the abnormality determination unit 56.

[0093] The following describes a method for calculating the first heat exchange amount Qr, which is the heat exchange amount in the refrigerant circuit 3. First, the state quantity calculation unit 60 calculates the enthalpy difference between the inlet and outlet of the heat exchanger HE using the operating state information (pressure, temperature) acquired by the operating state information acquisition unit 51. The flow rate calculation unit 54 calculates the refrigerant flow rate using the displacement and rotation speed of the compressor 31 acquired by the operating state information acquisition unit 51 and the refrigerant density calculated by the physical property value calculation unit 53. The memory unit 6 stores a p-h diagram of the refrigerant circulating through the refrigerant circuit 3, and this p-h diagram may be used to derive the enthalpy difference between the inlet and outlet of the heat exchanger HE.

[0094] Next, the capacity calculation unit 55 calculates the first heat exchange amount Qr by the following formula (11) using the calculation results of the state quantity calculation unit 60 and the flow rate calculation unit 54. In formula (11), Gr is the flow rate of the refrigerant calculated by the flow rate calculation unit 54. Also, Δh is the enthalpy difference between the inlet and outlet of the heat exchanger HE calculated by the state quantity calculation unit 60.

[0095]

[0096] Next, a method for calculating the second heat exchange amount Qb, which is the heat exchange amount in the fluid circuit 4, will be described. First, the physical property value calculation unit 53 calculates the density, specific heat, and kinematic viscosity of the heat exchange fluid and the temperature difference between the inlet and outlet of the heat exchanger HE using the operating state information (pressure and temperature) acquired by the operating state information acquisition unit 51 and the setting information (type and concentration) of the heat exchange fluid acquired by the setting information acquisition unit 52. Furthermore, the flow rate calculation unit 54 calculates the flow rate of the heat exchange fluid using the physical property values ​​calculated by the physical property value calculation unit 53 and the pressure difference between the inlet and outlet of the heat exchanger HE acquired by the operating state information acquisition unit 51. Here, the calculation of the flow rate of the heat exchange fluid in detecting a change in the concentration of the heat exchange fluid may be performed using an approximate formula derived from the physical property values ​​of the heat exchange fluid calculated using the setting information (type and concentration) and temperature of the heat exchange fluid. The differential pressure between the inlet and outlet of the heat exchanger HE of the fluid circuit 4 may be a value measured using a differential pressure gauge.

[0097] Next, the capacity calculation unit 55 calculates the first heat exchange amount Qr using the calculation results of the physical property value calculation unit 53 and the flow rate calculation unit 54, according to the following formula (12): In formula (12), Gb is the flow rate of the heat-exchanged fluid calculated by the flow rate calculation unit 54. Furthermore, ρ is the density of the heat-exchanged fluid calculated by the physical property value calculation unit 53, V is the flow rate of the heat-exchanged fluid calculated by the flow rate calculation unit 54, c is the specific heat of the heat-exchanged fluid calculated by the physical property value calculation unit 53, and ΔT is the temperature difference of the heat-exchanged fluid between the inlet and outlet of the heat exchanger HE calculated by the physical property value calculation unit 53.

[0098]

[0099] If the abnormality determination unit 56 detects a difference between the first heat exchange amount Qr and the second heat exchange amount Qb, it means that the concentration of the heat exchange fluid has changed since the beginning of operation, and the density ρ, flow rate V, and specific heat c of the heat exchange fluid have changed in the fluid circuit 4. In other words, the occurrence of a change in the concentration of the heat exchange fluid can be detected from the difference between the first heat exchange amount Qr and the second heat exchange amount Qb.

[0100] If the abnormality determination unit 56 detects that the concentration of the heat exchange fluid has changed, for example, if the difference in the heat exchange amount between the first heat exchange amount Qr and the second heat exchange amount Qb is greater than or equal to a predetermined value, the equipment drive control unit 58 may stop operation of each equipment provided in the refrigeration cycle device 2.

[0101] When the abnormality judgment unit 56 detects a change in the concentration of the heat exchange fluid, in addition to stopping the operation of each device equipped in the refrigeration cycle device 2, it may calculate the concentration change and calculate a correction amount for at least one of the setting information and freezing temperature of the heat exchange fluid, and notify the user.

[0102] When a difference occurs between the first heat exchange amount Qr and the second heat exchange amount Qb, that is, when a difference occurs between the second heat exchange amount Qb at the beginning of operation of the refrigeration cycle apparatus 2 and the current second heat exchange amount Qb, the second heat exchange amount Qb changes due to changes in the density ρ, flow rate V, and specific heat c in equation (12). Therefore, the concentration of the heat exchange fluid can be calculated using the changes in the density ρ, flow rate V, and specific heat c from the beginning of operation of the refrigeration cycle apparatus 2 to the present.

[0103] FIG. 10 is a graph illustrating the specific gravity characteristics corresponding to the type and concentration of the heat-exchanged fluid. In FIG. 10, the horizontal axis represents the concentration of the heat-exchanged fluid, and the vertical axis represents the specific gravity of the heat-exchanged fluid. Here, specific gravity is the ratio between the density of the heat-exchanged fluid and the density of a reference substance (e.g., water). Therefore, density and specific gravity are correlated, and specific gravity changes as density changes. That is, the capacity calculation unit 55 calculates the change in specific gravity corresponding to a change in density and can calculate the changed concentration from the changed specific gravity of the heat-exchanged fluid using the relationship illustrated in FIG. 10. Furthermore, the freezing temperature of the heat-exchanged fluid can be derived from the concentration of the heat-exchanged fluid, as illustrated in FIG. 11. Therefore, the capacity calculation unit 55 can calculate not only the change in concentration of the heat-exchanged fluid but also the change in freezing temperature of the heat-exchanged fluid by calculating the difference between the first heat exchange amount Qr and the second heat exchange amount Qb.

[0104] In this way, the capacity calculation unit 55 can calculate the concentration and freezing temperature of the heat exchange fluid that have changed since the initial operation of the refrigeration cycle device 2, and can therefore calculate a correction amount for at least one of the setting information and the freezing temperature of the heat exchange fluid. The correction amount calculated by the capacity calculation unit 55 may be notified to the user by the notification unit 7.

[0105] Even when a change in the concentration of the heat exchange fluid occurs, for example, when the concentration changes due to evaporation or moisture absorption, the capacity calculation unit 55 can calculate a correction amount for the concentration of the heat exchange fluid to make the capacity of the refrigeration cycle device 2 equivalent to that at the beginning of operation. Furthermore, the calculation result is notified to the user by the notification unit 7, so that the user can grasp the change in the concentration of the heat exchange fluid and can correct the concentration of the heat exchange fluid to make the refrigeration cycle device 2 output a predetermined capacity.

[0106] Furthermore, even if the concentration of the heat exchange fluid changes due to evaporation or moisture absorption of the heat exchange fluid after installation, an abnormality is reported, and continued operation of the refrigeration cycle device 2 can be prevented when the physical properties of the heat exchange fluid are abnormal, thereby preventing breakdowns and accidents. Furthermore, by performing periodic maintenance, it is possible to eliminate the need to check the concentration of the heat exchange fluid.

[0107] In the above example, the concentration and freezing temperature of the heat-exchanged fluid are calculated by the capacity calculation unit 55. Alternatively, a data table showing the relationship between the concentration and freezing temperature of the heat-exchanged fluid and a data table showing the relationship between the concentration and freezing temperature of the heat-exchanged fluid may be stored in the storage unit 6. In this case, the capacity calculation unit 55 may determine the correction amounts for the concentration and freezing temperature of the heat-exchanged fluid by referring to each data table.

[0108] (Additional Notes) The present disclosure has been described above using embodiments, but the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Various changes or improvements can be made to the above embodiments without departing from the gist of the present disclosure, and forms incorporating such changes or improvements are also included in the technical scope of the present disclosure. Furthermore, the above embodiments may be combined as appropriate.

[0109] The control device, the refrigeration cycle device including the same, the refrigeration cycle system including the same, the control method, and the control program according to the above-described embodiments can be understood, for example, as follows: A control device (5) according to a first aspect of the present disclosure is a control device for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, and includes a temperature acquisition unit (51) that acquires the temperature of the heat-exchanged fluid, a pressure acquisition unit (52) that acquires the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, a setting information acquisition unit (52) that acquires setting information on the type and concentration of the heat-exchanged fluid, and a temperature acquisition unit (53) that acquires setting information on the type and concentration of the heat-exchanged fluid acquired by the temperature acquisition unit. The heat exchanger is provided with a physical property value calculation unit (53) that calculates the density and kinetic viscosity of the heat-exchanged fluid using the temperature and the setting information acquired by the setting information acquisition unit, and a flow rate calculation unit (54) that calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property value calculation unit in a flow rate calculation formula that includes density, kinetic viscosity, and differential pressure as parameters.

[0110] According to the control device of the present disclosure, the temperature acquisition unit and the pressure acquisition unit acquire the temperature and differential pressure of the heat-exchanged fluid and acquire setting information on the type and concentration of the heat-exchanged fluid. The physical property value calculation unit calculates the density and kinematic viscosity of the heat-exchanged fluid using the temperature acquired by the temperature acquisition unit, the pressure acquired by the pressure acquisition unit, and the setting information acquired by the setting information acquisition unit. The flow rate calculation unit calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinematic viscosity, and differential pressure calculated by the physical property value calculation unit in a flow rate calculation formula including the density, kinematic viscosity, and differential pressure as parameters. This makes it possible to determine the flow rate of the heat-exchanged fluid without providing a flow meter, i.e., while suppressing an increase in the cost of the refrigeration cycle device. In addition, the flow rate of the heat exchange fluid can be determined based on the temperature, differential pressure, type, and concentration of the heat exchange fluid, so the flow rate of the heat exchange fluid can be determined even when the refrigerant circuit on the refrigerant side is not driven.

[0111] In the control device according to the second aspect of the present disclosure, in the first aspect, the flow rate calculation formula is a calculation formula derived from an approximation formula showing the relationship between the Reynolds number of the heat exchange fluid and pressure loss / dynamic pressure, which is derived using a plurality of data in which temperature and differential pressure are associated for each combination of type and concentration of the heat exchange fluid.

[0112] According to the control device of the present disclosure, the flow rate calculation formula is a calculation formula derived from an approximation formula showing the relationship between the Reynolds number of the heat exchange fluid and the pressure loss / dynamic pressure, which is derived using multiple data sets in which temperature and differential pressure are associated for each combination of the type and concentration of the heat exchange fluid. That is, the flow rate of the heat exchange fluid is calculated using a predetermined calculation formula that is dimensionless. This allows the flow rate of the heat exchange fluid to be accurately calculated without being limited by the type or concentration of the heat exchange fluid that the user arbitrarily sets.

[0113] In the control device according to the third aspect of the present disclosure, in the first or second aspect, the temperature acquisition unit acquires the measurement result of a first temperature measurement unit (T1) that measures a first temperature of the heat-exchanged fluid flowing into the heat exchanger and the measurement result of a second temperature measurement unit (T2) that measures a second temperature of the heat-exchanged fluid flowing out of the heat exchanger, and the physical property value calculation unit calculates the temperature average of the first temperature and the second temperature.

[0114] According to the control device of the present disclosure, the temperature acquisition unit acquires the measurement result of the first temperature measurement unit that measures the temperature of the heat-exchanged fluid flowing into the heat exchanger and the measurement result of the second temperature measurement unit that measures the temperature of the heat-exchanged fluid flowing out of the heat exchanger, and the physical property value calculation unit calculates the average of the first temperature and the second temperature measurement. This makes it possible to more accurately acquire the temperature of the heat-exchanged fluid, and therefore to more accurately calculate the flow rate of the heat-exchanged fluid.

[0115] The control device according to the fourth aspect of the present disclosure, in any of the first to third aspects, includes an equipment drive control unit (58) that controls a compressor (31) that compresses the refrigerant, a pressure reducer (33) that decompresses the refrigerant, and a pump (41) that delivers the heat exchange fluid, using the calculation result of the flow rate calculation unit as one of the parameters.

[0116] According to the control device of the present disclosure, the control device includes an equipment drive control unit that controls a compressor that compresses a refrigerant, a pressure reducer that decompresses the refrigerant, and a pump that delivers a heat exchange fluid based on the calculation results of the flow rate calculation unit, thereby making it possible to appropriately control the state of the refrigerant flowing through the heat exchanger and the flow rate of the heat exchange fluid.

[0117] The control device according to the fifth aspect of the present disclosure, in any of the first to fourth aspects, is provided with an abnormality determination unit (56) that determines whether or not there is an abnormality in the flow rate of the heat exchange fluid based on the calculation result of the flow rate calculation unit.

[0118] According to the control device of the present disclosure, the control device includes an abnormality determination unit that determines whether or not there is an abnormality in the flow rate of the heat exchange fluid based on the calculation result of the flow rate calculation unit, thereby making it possible to determine an abnormality in the flow rate of the heat exchange fluid and to prevent the refrigeration cycle device from continuing operation when there is an abnormality.

[0119] The control device according to the sixth aspect of the present disclosure, in any of the first to fifth aspects, comprises a capacity calculation unit (55) that calculates a first heat exchange amount, which is the heat exchange amount of the refrigerant in the heat exchanger, and a second heat exchange amount, which is the heat exchange amount of the heat-exchanged fluid in the heat exchanger, and a concentration change detection unit (57) that detects a change in concentration of the heat-exchanged fluid based on the difference in heat exchange amount between the first heat exchange amount and the second heat exchange amount.

[0120] According to the control device disclosed herein, a capacity calculation unit calculates a first heat exchange amount, which is the heat exchange amount of the refrigerant in the heat exchanger, and a second heat exchange amount, which is the heat exchange amount of the heat-exchanged fluid in the heat exchanger, and a concentration change detection unit detects a change in the concentration of the heat-exchanged fluid based on the difference between the first heat exchange amount and the second heat exchange amount. This makes it possible to prevent continued operation of the refrigeration cycle device when the physical properties of the heat-exchanged fluid are abnormal, thereby preventing malfunctions and accidents. Furthermore, by performing periodic maintenance, it is possible to eliminate the need to check the concentration of the heat-exchanged fluid.

[0121] A refrigeration cycle device according to a seventh aspect of the present disclosure includes the control device (5) of any one of the first to sixth aspects.

[0122] A refrigeration cycle system according to an eighth aspect of the present disclosure includes the refrigeration cycle device (2) according to the seventh aspect, and a fluid circuit (4) through which the heat exchange fluid circulates.

[0123] A control method according to a ninth aspect of the present disclosure is a control method for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger (HE), the control method including a temperature acquisition step of acquiring a temperature of the heat-exchanged fluid; a pressure acquisition step of acquiring a pressure of the heat-exchanged fluid flowing into the heat exchanger and a pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition step of acquiring setting information on the type and concentration of the heat-exchanged fluid; and a temperature acquisition step of acquiring the temperature acquired by the temperature acquisition step. and the setting information acquired by the setting information acquisition step, and a flow rate calculation step of calculating a differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculating a flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property calculation step in a flow rate calculation formula including density, kinetic viscosity, and differential pressure as parameters.

[0124] A control program according to a tenth aspect of the present disclosure is a control program for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger (HE), the control program including a temperature acquisition process for acquiring the temperature of the heat-exchanged fluid; a pressure acquisition process for acquiring the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition process for acquiring setting information on the type and concentration of the heat-exchanged fluid; and a temperature acquisition process for acquiring the temperature acquired by the temperature acquisition process. The computer is caused to execute a physical property calculation process that calculates the density and kinetic viscosity of the heat-exchanged fluid using the setting information acquired by the setting information acquisition process, and a flow rate calculation process that calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property calculation process in a flow rate calculation formula that includes density, kinetic viscosity, and differential pressure as parameters.

[0125] REFRIGERATION CYCLE SYSTEM 2 REFRIGERATION CYCLE DEVICE 3 REFRIGERANTE CIRCUIT 4 FLUID CIRCUIT 5 CONTROL DEVICE 5a CPU 5b Auxiliary storage device (ROM) 5c Main storage device (RAM) 5d Communication interface 5e Input / output unit 5f Bus 6 Storage unit 7 Notification unit 10 Refrigeration cycle system 31 Compressor 32 Heat exchanger 33 Pressure reducer 41 Pump 42 Equipment load 51 Operation state information acquisition unit 52 Setting information acquisition unit 53 Physical property value calculation unit 54 Flow rate calculation unit 55 Capacity calculation unit 56 Abnormality determination unit 57 Abnormality processing unit 58 Equipment drive control unit 60 State quantity calculation unit HE Heat exchanger P1 to P4 Pressure sensors T1 to T4 Temperature sensors

Claims

1. A control device for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, comprising: a temperature acquisition unit that acquires the temperature of the heat-exchanged fluid; a pressure acquisition unit that acquires the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition unit that acquires setting information on the type and concentration of the heat-exchanged fluid; a physical property value calculation unit that calculates the density and kinetic viscosity of the heat-exchanged fluid using the temperature acquired by the temperature acquisition unit and the setting information acquired by the setting information acquisition unit; and a flow rate calculation unit that calculates the differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates the flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property value calculation unit for a flow rate calculation formula including density, kinetic viscosity, and differential pressure as parameters.

2. The control device described in claim 1, wherein the flow rate calculation formula is a calculation formula derived from an approximation formula showing the relationship between the Reynolds number of the heat exchange fluid and the pressure loss / dynamic pressure, derived using multiple data in which temperature and differential pressure correspond to each combination of type and concentration of the heat exchange fluid.

3. The control device described in claim 1, wherein the temperature acquisition unit acquires the measurement result of a first temperature measurement unit that measures a first temperature of the heat exchange fluid flowing into the heat exchanger and the measurement result of a second temperature measurement unit that measures a second temperature of the heat exchange fluid flowing out of the heat exchanger, and the physical property value calculation unit calculates the temperature average of the first temperature and the second temperature.

4. The control device according to claim 1, further comprising an equipment drive control unit that controls a compressor that compresses the refrigerant, a pressure reducer that depressurizes the refrigerant, and a pump that discharges the heat exchange fluid, using the calculation result of the flow rate calculation unit as one of the parameters.

5. The control device according to claim 1, further comprising an abnormality determination unit which determines whether or not there is an abnormality in the flow rate of the heat exchange fluid based on the calculation result of the flow rate calculation unit.

6. The control device according to claim 1, further comprising: a capacity calculation unit which calculates a first heat exchange amount, which is the heat exchange amount of the refrigerant in the heat exchanger, and a second heat exchange amount, which is the heat exchange amount of the heat-exchanged fluid in the heat exchanger; and a concentration change detection unit which detects a change in concentration of the heat-exchanged fluid based on the difference in heat exchange amount between the first heat exchange amount and the second heat exchange amount.

7. A refrigeration cycle device equipped with the control device according to claim 1.

8. A refrigeration cycle system comprising: the refrigeration cycle device according to claim 7; and a fluid circuit through which the heat exchange fluid circulates.

9. A control method for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, the control method comprising: a temperature acquisition step of acquiring a temperature of the heat-exchanged fluid; a pressure acquisition step of acquiring a pressure of the heat-exchanged fluid flowing into the heat exchanger and a pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition step of acquiring setting information on the type and concentration of the heat-exchanged fluid; a physical property calculation step of calculating a density and kinetic viscosity of the heat-exchanged fluid using the temperature acquired in the temperature acquisition step and the setting information acquired in the setting information acquisition step; and a flow rate calculation step of calculating a differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculating a flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated in the physical property calculation step for a flow rate calculation formula including density, kinetic viscosity, and differential pressure as parameters.

10. A control program for a refrigeration cycle device that supplies a heat-exchanged fluid at a desired temperature by performing heat exchange between a refrigerant and a heat-exchanged fluid in a heat exchanger, comprising: a temperature acquisition process that acquires a temperature of the heat-exchanged fluid; a pressure acquisition process that acquires a pressure of the heat-exchanged fluid flowing into the heat exchanger and a pressure of the heat-exchanged fluid flowing out of the heat exchanger; a setting information acquisition process that acquires setting information on a type and concentration of the heat-exchanged fluid; a physical property value calculation process that calculates a density and a kinetic viscosity of the heat-exchanged fluid using the temperature acquired by the temperature acquisition process and the setting information acquired by the setting information acquisition process; and a flow rate calculation process that calculates a differential pressure between the pressure of the heat-exchanged fluid flowing into the heat exchanger and the pressure of the heat-exchanged fluid flowing out of the heat exchanger, and calculates a flow rate of the heat-exchanged fluid by using the density, kinetic viscosity, and differential pressure of the heat-exchanged fluid calculated by the physical property value calculation process for a flow rate calculation formula including density, kinetic viscosity, and differential pressure as parameters. A control program for causing a computer to execute the above.

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