Refrigeration Cycle Equipment

Abstract

This refrigeration cycle device comprises: a compressor that compresses and discharges a working fluid; a condenser that condenses the working fluid discharged from the compressor; an inter-refrigerant heat exchanger that is equipped with a condensed fluid flow path in which the working fluid flowing from the condenser flows, and a low-pressure flow path in which flows a working fluid having a lower pressure than the working fluid flowing in the condensed fluid flow path, the inter-refrigerant heat exchanger performing heat exchange between the working fluid flowing in the condensed fluid flow path and the working fluid flowing in the low-pressure flow path; a first throttle device that reduces the pressure of the working fluid flowing from the condensed fluid flow path of the inter-refrigerant heat exchanger; an evaporator that causes evaporation of the working fluid pressure-reduced by the first throttle device; an optical sensor that is provided to piping connecting the outlet of the condensed fluid flow path of the inter-refrigerant heat exchanger to the first throttle device, and that is equipped with a projection device which projects light onto the working fluid flowing in the piping and a detector which detects transmitted light; and a control device that, on the basis of the results of detection by the optical sensor, measures the concentration of a component contained in the working fluid.

Description

[Technical field]

[0001] The present disclosure relates to a refrigeration cycle device, and more particularly to a refrigeration cycle device equipped with an optical sensor. [Background technology]

[0002] In a typical refrigeration cycle device, the refrigerant discharged from the compressor is condensed in a condenser to become a liquid refrigerant. The liquid refrigerant is then decompressed by a throttling device to become a gas-liquid two-phase state in which gas refrigerant and liquid refrigerant are mixed. The liquid refrigerant in the gas-liquid two-phase state is then evaporated in an evaporator to become a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out from the evaporator is sucked into the compressor, compressed to become a high-temperature, high-pressure gas refrigerant, and discharged from the compressor again. In the refrigeration cycle device, this cycle is repeated.

[0003] In a refrigeration cycle device, the refrigerant discharged from the compressor may contain an excessive amount of refrigerant oil. In addition, in a refrigeration cycle device, when a non-azeotropic refrigerant mixture is used as the working fluid, it is known that the circulating composition ratio of the refrigerant changes depending on the operating conditions such as cooling or heating. When the circulating composition ratio of the refrigerant changes, the saturation temperature of the refrigerant cannot be detected accurately, and this influence may cause an excessive amount of liquid refrigerant to flow into the compressor. In this case, the refrigerant oil in the compressor is diluted and seized, which may cause the compressor to break down.

[0004] Therefore, in a refrigeration cycle device, it is important to measure the concentration of components contained in the working fluid, such as the concentration of refrigerating machine oil in the working fluid or the circulating composition ratio of a mixed refrigerant. Spectroscopic measurement means using an optical sensor are known as a means for measuring the component concentration of the working fluid (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 04-095276 Summary of the Invention [Problem to be solved by the invention]

[0006] In the refrigeration cycle device of Patent Document 1, an optical sensor is provided in the refrigerant piping from the condenser to the receiver. In such a refrigeration cycle device, when low-load operation is performed, the degree of subcooling at the condenser outlet decreases, and gas refrigerant is mixed into the refrigerant flowing in the refrigerant piping from the condenser to the receiver. This forms a gas-liquid interface in the refrigerant piping, and the component concentrations of the working fluid may not be accurately measured due to light scattering or differences in flow speed between the liquid phase and the gas phase.

[0007] The present disclosure is intended to solve the above-mentioned problems, and has an object to improve the measurement accuracy of component concentrations of a working fluid in a refrigeration cycle device. [Means for solving the problem]

[0008] The refrigeration cycle apparatus according to the present disclosure includes a compressor which compresses and discharges a working fluid, a condenser which condenses the working fluid discharged from the compressor, a condensed fluid flow path through which the working fluid discharged from the condenser flows, and a low-pressure flow path through which a working fluid of a lower pressure than the working fluid flowing through the condensed fluid flow path flows, and includes an inter-refrigerant heat exchanger which performs heat exchange between the working fluid flowing through the condensed fluid flow path and the working fluid flowing through the low-pressure flow path, a first throttling device which reduces the pressure of the working fluid discharged from the condensed fluid flow path of the inter-refrigerant heat exchanger, an evaporator which evaporates the working fluid reduced in pressure by the first throttling device, an optical sensor which is provided in a pipe connecting an outlet of the condensed fluid flow path of the inter-refrigerant heat exchanger and the first throttling device, and which includes an illuminator which irradiates light onto the working fluid flowing through the pipe and a detector which detects transmitted light, and a control device which measures the concentration of components contained in the working fluid based on the detection result of the optical sensor. a flow path switching valve that switches a flow path of the working fluid discharged from the compressor; and a flow path switching mechanism that switches the flow of the working fluid such that the refrigerant-to-refrigerant heat exchanger is disposed between the condenser and the optical sensor, regardless of the switching of the flow path of the working fluid by the flow path switching valve. Equipped with. Effect of the Invention

[0009] According to the refrigeration cycle device of the present disclosure, an optical sensor is provided in the pipe connecting the outlet of the condensed fluid passage of the refrigerant-to-refrigerant heat exchanger and the first throttling device, so that the refrigerant flowing through the pipe is always in a liquid state, improving the detection accuracy of the transmitted light by the optical sensor, thereby improving the measurement accuracy of the component concentrations of the working fluid. [Brief description of the drawings]

[0010] [Figure 1] 1 is a refrigerant circuit diagram of a refrigeration cycle device according to a first embodiment. [Diagram 2] 1 is a schematic configuration diagram of an optical sensor according to a first embodiment. [Diagram 3] 1 is a control block diagram of a refrigeration cycle device according to a first embodiment. [Figure 4] 1 is a graph showing an example of the light absorption characteristics of two components contained in a working fluid. [Diagram 5] FIG. 13 is a diagram illustrating detection of transmitted light through a working fluid in a conventional example. [Figure 6] FIG. 6 is a refrigerant circuit diagram of a refrigeration cycle device according to a second embodiment. [Figure 7] FIG. 11 is a refrigerant circuit diagram of a refrigeration cycle device according to a third embodiment. [Figure 8] 4 is a Mollier diagram when the refrigerant flowing through the refrigerant pipe becomes a gas-liquid two-phase state due to pressure loss of the second throttle device. [Figure 9] FIG. 11 is a Mollier diagram of a refrigeration cycle device according to a third embodiment. [Figure 10] FIG. 11 is a refrigerant circuit diagram of a refrigeration cycle device according to a fourth embodiment. [Figure 11] FIG. 11 is a diagram for explaining the flow of refrigerant during cooling operation of the refrigeration cycle device according to the fourth embodiment. [Figure 12] FIG. 11 is a diagram for explaining the flow of refrigerant during heating operation of the refrigeration cycle device according to the fourth embodiment. [Figure 13] FIG. 11 is a refrigerant circuit diagram of a refrigeration cycle device according to a fifth embodiment. [Figure 14] FIG. 4 is a refrigerant circuit diagram of a refrigeration cycle device according to a first modified example. [Figure 15] FIG. 11 is a schematic diagram showing an installation direction of an optical sensor in a refrigeration cycle device according to a second modified example. [Figure 16] FIG. 4 is a diagram illustrating the state of a working fluid at a low flow rate. [Figure 17] FIG. 11 is a schematic diagram showing an installation direction of an optical sensor in a refrigeration cycle device according to a third modified example. [Figure 18] FIG. 11 is a refrigerant circuit diagram of a refrigeration cycle device according to a fourth modified example. [Figure 19] FIG. 11 is a refrigerant circuit diagram of a refrigeration cycle device according to a fifth modified example. [Figure 20] FIG. 13 is a refrigerant circuit diagram of a refrigeration cycle device according to a sixth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a refrigeration cycle device according to an embodiment of the present disclosure will be described with reference to the drawings. Hereinafter, in the drawings including FIG. 1, the same reference numerals are used to denote the same or corresponding configurations, and are common throughout the entire embodiment described below. In addition, to facilitate understanding, terms expressing directions (e.g., "up," "down," "right," "left," "front," "rear," etc.) are used as appropriate, but these notations are merely used for the convenience of explanation and do not limit the arrangement and orientation of the device or parts. Furthermore, the forms of the components shown in the entire specification are merely examples, and are not limited to the forms described in the specification.

[0012] Embodiment 1 <Configuration of refrigeration cycle device> Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100 according to the first embodiment. The refrigeration cycle apparatus 100 of the present embodiment is a refrigeration device that cools a warehouse, a showcase, a refrigerator, or the like. As shown in Fig. 1, the refrigeration cycle apparatus 100 includes a heat source unit 10 and a load unit 20. The heat source unit 10 and the load unit 20 each have separate housings and are installed in different locations, for example, outdoors and indoors.

[0013] The heat source unit 10 includes a compressor 1, a condenser 3, a first fan 31, a refrigerant heat exchanger 4, a cooling throttling device 40, an optical sensor 8, and a refrigerant tank 7. The load unit 20 includes a first throttling device 51, an evaporator 6, and a second fan 61.

[0014] The compressor 1, the condenser 3, the refrigerant heat exchanger 4, the first throttling device 51, the evaporator 6, and the refrigerant tank 7 are connected in this order by piping to form a refrigerant circuit of the refrigeration cycle device 100. The refrigerant tank 7 is not an essential component and may be omitted. The refrigerant flowing through the refrigerant circuit is a non-azeotropic mixed refrigerant obtained by mixing at least two or more types of refrigerants having different boiling points, such as propylene-based refrigerants such as tetrafluoropropene, ethylene-based refrigerants such as difluoroethylene, ethane-based refrigerants such as tetrafluoroethane, propane, or DME (dimethyl ether). Examples of the olefin-based refrigerant include HFO1234yf and HFO1234ze(E). In addition, the refrigerant may be a single refrigerant such as R32, HFO1234yf, HFF1123zf, or propane, or a mixed refrigerant obtained by mixing two or more of these.

[0015] The refrigeration cycle apparatus 100 further includes a control device 200 that controls the operating state of the refrigeration cycle apparatus 100. In FIG. 1, the heat source unit 10 is configured to include the control device 200, but the control device 200 may be provided in the load unit 20, or the heat source unit 10 and the load unit 20 may be configured to have individual control devices 200 that communicate with each other. The refrigeration cycle apparatus 100 may further include an indoor temperature sensor that detects the temperature of the space to be cooled, an outdoor air temperature sensor that detects the outdoor air temperature, and a sensor that detects the temperature or pressure of the refrigerant flowing through each heat exchanger. For example, the refrigeration cycle apparatus 100 may include an inlet temperature sensor that detects the refrigerant temperature at the refrigerant inlet of the evaporator 6, and an outlet temperature sensor that detects the refrigerant temperature at the refrigerant outlet of the evaporator 6.

[0016] The compressor 1 sucks in a refrigerant, compresses it, and discharges it in a high-temperature, high-pressure state. The refrigerant discharged from the compressor 1 is sent to the condenser 3. The compressor 1 is, for example, a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor. Refrigerating machine oil for lubricating sliding parts is stored inside the compressor 1. The refrigerating machine oil is, for example, polyalkylene glycol, polyol ester, polyvinyl ether, alkylbenzene, or mineral oil, and one having high compatibility with the refrigerant, high stability, and the like is used.

[0017] The condenser 3 exchanges heat between the refrigerant flowing therein and air, and condenses and liquefies the refrigerant. The condenser 3 is, for example, a fin-and-tube heat exchanger or a microchannel heat exchanger. In order to increase the efficiency of heat exchange between the refrigerant and air in the condenser 3, a first fan 31 is disposed adjacent to the condenser 3. The condenser 3 may be, for example, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-tube heat exchanger, a plate heat exchanger, or the like that exchanges heat between a heat medium such as water or brine and the refrigerant.

[0018] The first fan 31 supplies air to the condenser 3. The first fan 31 is a propeller fan, a crossflow fan, or a multi-blade centrifugal fan. When the condenser 3 exchanges heat not with air but with a heat medium and a refrigerant, the first fan 31 is omitted and a pump that circulates the heat medium is provided instead.

[0019] The inter-refrigerant heat exchanger 4 has a condensed fluid flow path 41 through which the high-temperature refrigerant flowing out from the condenser 3 flows, and a low-pressure flow path 42 through which a refrigerant with a lower pressure and temperature than the refrigerant flowing through the condensed fluid flow path 41 flows. The inter-refrigerant heat exchanger 4 exchanges heat between the refrigerant flowing through the condensed fluid flow path 41 and the refrigerant flowing through the low-pressure flow path 42. The inter-refrigerant heat exchanger 4 is a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-pipe heat exchanger, or a plate heat exchanger.

[0020] The inter-refrigerant heat exchanger 4 is provided downstream of the condenser 3 in the refrigerant flow direction. A refrigerant inlet of a condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 is connected to a refrigerant outlet of the condenser 3, and high-temperature refrigerant flowing out from the condenser 3 flows through the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. A refrigerant outlet of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 is connected to a first throttling device 51 by a refrigerant piping 501.

[0021] Further, a branch pipe 502 is connected to the refrigerant pipe 501 between the refrigerant outlet of the condensed fluid flow path 41 and the optical sensor 8. The branch pipe 502 connects the refrigerant pipe 501 and a refrigerant inlet of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. A part of the refrigerant that flows out from the condensed fluid flow path 41 of the inter-refrigerant heat exchanger 4 and flows through the refrigerant pipe 501 is branched to the branch pipe 502.

[0022] The branch pipe 502 is provided with a cooling throttling device 40. The cooling throttling device 40 expands and reduces the pressure of the refrigerant flowing through the branch pipe 502, and causes the refrigerant to flow into the low-pressure flow path 42 of the refrigerant-to-refrigerant heat exchanger 4 as a low-temperature refrigerant. The cooling throttling device 40 is, for example, an electronic expansion valve whose opening degree can be controlled. Note that the cooling throttling device 40 is not limited to an electronic expansion valve, and may be a mechanical expansion valve employing a diaphragm in a pressure receiving portion, a capillary tube, or the like.

[0023] The refrigerant outlet of the low-pressure flow path 42 is connected to the refrigerant outlet of the evaporator 6 by a refrigerant pipe 503. The refrigerant flowing out from the refrigerant outlet of the low-pressure flow path 42 merges with the refrigerant flowing out from the evaporator 6 and flows into the refrigerant tank 7.

[0024] The first throttling device 51 expands and reduces the pressure of the refrigerant flowing through the refrigerant pipe 501. The first throttling device 51 is, for example, an electronic expansion valve whose opening degree can be controlled. Note that the first throttling device 51 is not limited to an electronic expansion valve, and may be a mechanical expansion valve employing a diaphragm in a pressure receiving portion, a capillary tube, or the like.

[0025] The evaporator 6 exchanges heat between the refrigerant flowing therein and the air, and evaporates and vaporizes the refrigerant. The evaporator 6 is, for example, a fin-and-tube heat exchanger or a microchannel heat exchanger. In order to increase the efficiency of heat exchange between the refrigerant and the outdoor air in the evaporator 6, a second fan 61 is disposed adjacent to the evaporator 6. The evaporator 6 may be, for example, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-tube heat exchanger, a plate heat exchanger, or the like that exchanges heat between a heat medium such as water or brine and the refrigerant.

[0026] The second fan 61 supplies air to the evaporator 6. The second fan 61 is a propeller fan, a crossflow fan, or a multi-blade centrifugal fan. When the evaporator 6 exchanges heat between a heat medium and a refrigerant instead of air, the second fan 61 is omitted, and a pump that circulates the heat medium is provided instead.

[0027] The refrigerant tank 7 is provided between the refrigerant outlet of the evaporator 6 and the suction port of the compressor 1. The refrigerant tank 7 has a refrigerant storage function for storing excess refrigerant, and a gas-liquid separation function for separating the gas-liquid two-phase refrigerant flowing from the evaporator 6 into the refrigerant tank 7, discharging the gas refrigerant to the compressor 1, and retaining the liquid refrigerant. The refrigerant tank 7 is, for example, a volumetric tank or an accumulator with an inner diameter larger than the inner diameter of the suction pipe connected to the suction port of the compressor 1. The refrigeration cycle apparatus 100 can prevent liquid compression from being performed in the compressor 1 by the gas-liquid separation function of the refrigerant tank 7.

[0028] The optical sensor 8 is provided in the refrigerant pipe 501 that connects the refrigerant heat exchanger 4 and the first throttling device 51. The optical sensor 8 irradiates light onto the working fluid flowing through the refrigerant pipe 501 and detects the intensity of the light transmitted through the working fluid. In this description, the term "working fluid" refers to the refrigerant flowing through the refrigerant circuit or the refrigerant flowing through the refrigerant circuit and refrigeration oil contained in the refrigerant.

[0029] FIG. 2 is a schematic diagram of the optical sensor 8 according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the refrigerant pipe 501 in a radial direction with the optical sensor 8 attached to the refrigerant pipe 501. As shown in FIG. 2, the optical sensor 8 includes a housing 80 attached to the refrigerant pipe 501, and an illuminator 81 and a detector 82 provided in the housing 80. The illuminator 81 and the detector 82 are arranged opposite each other with the refrigerant pipe 501 in between. The illuminator 81 has a light source such as an LED that emits light of a specific wavelength, and irradiates light based on an instruction from the control device 200. The detector 82 detects the light irradiated from the illuminator 81, converts the intensity of the detected light into an electric signal, and transmits it to the control device 200.

[0030] The refrigerant pipe 501 has openings 501a at positions facing the irradiator 81 and the detector 82. Each opening 501a is closed by a window plate 83 of the optical sensor 8. The window plate 83 is made of a material that is transparent to the irradiated light and can withstand the pressure of the working fluid within the operating range of the refrigeration cycle apparatus 100. Before the refrigerant is sealed in, the light irradiated from the irradiator 81 passes through the refrigerant pipe 501 via the window plate 83 and is transmitted to the detector 82.

[0031] The control device 200 controls the overall operation of the refrigeration cycle apparatus 100. The control device 200 is composed of a computer including a memory for storing data and programs required for control and a CPU for executing the programs, dedicated hardware such as an ASIC or an FPGA, or both.

[0032] 3 is a control block diagram of the refrigeration cycle apparatus 100 according to the embodiment 1. As shown in FIG.

[0033] The component concentration measuring unit 201 is a functional unit that is realized by the CPU of the control device 200 executing a program, or is realized by a dedicated processing circuit. The component concentration measuring unit 201 controls the irradiator 81 of the optical sensor 8 to irradiate light of a specific wavelength. The component concentration measuring unit 201 also measures the concentration of a component contained in the working fluid of the refrigeration cycle device 100 based on the detection result of the detector 82 of the optical sensor 8. The concentration of a component contained in the working fluid is, for example, the concentration of a refrigerating machine oil contained in the refrigerant, or the concentration of each refrigerant constituting the non-azeotropic refrigerant mixture. The component concentration measuring unit 201 transmits the measured component concentration to the operation control unit 202. The measurement of the component concentration of the working fluid by the component concentration measuring unit 201 will be described in detail later.

[0034] The operation control unit 202 is a functional unit that is realized by the CPU of the control device 200 executing a program or by a dedicated processing circuit. The operation control unit 202 controls each part of the refrigeration cycle device 100 based on setting information input via a remote control (not shown) or the like and detection results of various sensors such as an indoor temperature sensor or an outdoor air temperature sensor. Specifically, the operation control unit 202 controls the operation frequency of the compressor 1, the opening degree of the first throttling device 51 and the cooling throttling device 40, and the rotation speed of the first fan 31 and the second fan 61 based on the setting information and the detection results of each temperature sensor.

[0035] In addition, the operation control unit 202 of this embodiment controls the operation of the refrigeration cycle apparatus 100 according to the component concentration of the working fluid measured by the component concentration measurement unit 201. In general, when a liquid refrigerant is sucked into the compressor 1 during operation of the refrigeration cycle apparatus 100, liquid compression or dilution of the refrigeration oil occurs in the compressor 1, which causes a breakdown of the compressor 1. Therefore, when the concentration of the refrigeration oil in the working fluid is equal to or higher than a preset threshold, for example, the operation control unit 202 reduces the operating frequency of the compressor 1 or reduces the opening degree of the first throttling device 51 in order to prevent the refrigeration oil from running out in the compressor 1. As a result, the dryness of the refrigerant flowing out of the evaporator 6 increases, and the inflow of liquid refrigerant into the compressor 1 is suppressed.

[0036] Furthermore, when the refrigeration cycle apparatus 100 uses a non-azeotropic refrigerant mixture as the working fluid, the operation control unit 202 calculates a circulation composition ratio from the concentration of each refrigerant contained in the non-azeotropic refrigerant mixture measured by the component concentration measurement unit 201, and calculates an evaporation saturation temperature from the circulation composition ratio. Then, when the temperature of the refrigerant flowing out of the evaporator 6 is equal to or lower than the evaporation saturation temperature, the operation control unit 202 lowers the frequency of the compressor 1 or reduces the opening degree of the first throttling device 51. This increases the dryness of the refrigerant flowing out of the evaporator 6, and suppresses the inflow of liquid refrigerant into the compressor 1.

[0037] Furthermore, the difference between the liquid saturation temperature and the gas saturation temperature of a non-azeotropic refrigerant mixture changes depending on the composition ratio. Therefore, the operation control unit 202 may change the frequency of the compressor 1 and the opening degree of the first throttling device 51 according to the circulation composition ratio of the refrigerant to increase the refrigerant temperature at the refrigerant inlet of the evaporator 6. This makes it possible to suppress frosting and freezing due to a drop in the temperature of the evaporator 6.

[0038] The storage unit 203 is a volatile or non-volatile memory such as a RAM or a ROM. The storage unit 203 stores programs for executing the functions of the component concentration measurement unit 201 and the operation control unit 202, as well as various data such as parameters and threshold values ​​used in the control of each unit.

[0039] <Operation of the refrigeration cycle device> Next, returning to Fig. 1, the operation of the refrigeration cycle apparatus 100 will be described together with the flow of the refrigerant. The solid arrows in Fig. 1 indicate the flow of the refrigerant. When the compressor 1 of the refrigeration cycle apparatus 100 is driven, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 3.

[0040] In the condenser 3, heat exchange occurs between the high-temperature, high-pressure gas refrigerant that has flowed into the condenser 3 and air supplied by the first fan 31. The refrigerant that has undergone heat exchange in the condenser 3 is condensed to become a high-temperature, high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant.

[0041] The high-temperature, high-pressure liquid refrigerant or gas-liquid two-phase refrigerant flowing out of the condenser 3 flows into the condensed fluid flow path 41 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the condensed fluid flow path 41 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4, is cooled, and becomes a liquid refrigerant. Then, the refrigerant flows out of the condensed fluid flow path 41 of the inter-refrigerant heat exchanger 4.

[0042] The liquid refrigerant flowing out from the condensed fluid flow path 41 of the refrigerant heat exchanger 4 flows through the refrigerant pipe 501, and a part of it is diverted to the branch pipe 502. The liquid refrigerant flowing through the refrigerant pipe 501 passes through the optical sensor 8. The liquid refrigerant that has passed through the optical sensor 8 is decompressed by the first throttling device 51, becomes a low-pressure gas-liquid two-phase state, and flows into the evaporator 6.

[0043] In the evaporator 6, heat is exchanged between the refrigerant in a gas-liquid two-phase state that has flowed into the evaporator 6 and the air supplied by the second fan 61, and the liquid refrigerant in the gas-liquid two-phase state evaporates to become a low-pressure gas refrigerant. The air cooled by this heat exchange is supplied to the space to be cooled, and the space to be cooled is cooled.

[0044] On the other hand, the refrigerant branched to the branch pipe 502 is decompressed by the cooling throttle device 40 to become a medium-pressure liquid refrigerant or a gas-liquid two-phase refrigerant mainly composed of liquid, and flows into the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the condensed fluid flow path 41 to become a gas-liquid two-phase refrigerant or a low-pressure gas refrigerant, and flows out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The low-pressure gas-liquid two-phase refrigerant or gas refrigerant flowing out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 flows through the refrigerant pipe 503, and merges with the low-pressure gas refrigerant flowing out from the evaporator 6.

[0045] The low-pressure gas refrigerant flowing out from the evaporator 6 joins with the refrigerant flowing out from the low-pressure flow path 42 of the refrigerant-to-refrigerant heat exchanger 4, and flows into the refrigerant tank 7. Thereafter, the gas refrigerant separated in the refrigerant tank 7 is sucked into the compressor 1, compressed again by the compressor 1, and discharged. In the refrigeration cycle apparatus 100, this cycle is repeated.

[0046] Next, a method for measuring the component concentration of the working fluid in the refrigeration cycle device 100 of this embodiment will be described. First, the illuminator 81 of the optical sensor 8 emits light with a wavelength designed to match the components constituting the working fluid based on an instruction from the component concentration measuring unit 201 of the control device 200. The components constituting the working fluid are refrigerant and refrigeration oil. The light emitted from the illuminator 81 is irradiated to the working fluid flowing through the refrigerant pipe 501. The working fluid absorbs the light according to the wavelength sensitivity of the absorbance that differs for each component, and the remaining light is transmitted through the window plate 83 and detected by the detector 82. The detector 82 detects the intensity of the transmitted light for each wavelength and transmits the detected intensity of the transmitted light to the control device 200.

[0047] The component concentration measuring unit 201 of the control device 200 calculates the transmittance T from the intensity of the irradiated light irradiated from the irradiator 81 and the intensity of the transmitted light detected by the detector 82, and measures the concentration of the component contained in the working fluid. For example, the component concentration measuring unit 201 measures the concentration of the refrigeration oil from the transmittance T of a wavelength corresponding to the oil type in the ultraviolet region of wavelengths of 380 nm or less, where the refrigeration oil has a strong absorption wavelength. As another example, the component concentration measuring unit 201 measures the concentration of an olefin-based refrigerant, an ethylene-based refrigerant, or an ethane-based refrigerant from the transmittance T of a wavelength corresponding to the refrigerant type in the infrared region of wavelengths of 780 nm or more, where the refrigeration oil has a strong absorption wavelength.

[0048] Specifically, the constituent concentration measuring unit 201 calculates the constituent concentration using the Beer-Lambert law shown in the following equation (1).

number

[0049] In equation (1), T is the transmittance, A is the absorbance, and ε(λ i ) is the component-specific absorptance, c is the concentration, and l is the optical path length through the working fluid. In the present embodiment, l is the diameter of the refrigerant pipe 501. i ), and the optical path length l are known, so the concentration c can be calculated from equation (1).

[0050] FIG. 4 is a graph showing an example of the absorption characteristics of two components contained in the working fluid. In FIG. 4, the solid line shows the absorption characteristics of the first component C1, and the dashed line shows the absorption characteristics of the second component C2. The first component C1 and the second component C2 are components contained in the working fluid, for example, a refrigerant and a refrigerating machine oil, or two refrigerants constituting a mixed refrigerant. The component concentration measuring unit 201 sets, as the wavelength of the light irradiated by the irradiator 81, a first wavelength λ1 that is an absorption wavelength of the first component C1 and not an absorption wavelength of the second component C2, and a second wavelength λ2 that is an absorption wavelength of the second component C2 and not an absorption wavelength of the first component C1, instead of a third wavelength λ3 that is the same absorption wavelength of the first component C1 and the second component C2. By setting the measurement light in this way, the optical sensor 8 can accurately measure the transmitted light of each component.

[0051] Furthermore, by irradiating the fourth wavelength λ4, which is not absorbed by either the first component C1 or the second component C2, as reference light from the irradiator 81, it is possible to reduce the impact on measurement of a decrease in the luminous intensity of the detection light due to factors other than absorption by components contained in the working fluid.

[0052] Specifically, the component concentration measuring unit 201 may calculate the component concentration of the working fluid by the following formula (2) using the transmittance T0 of the reference light and the transmittance Ti of the measurement light.

number

[0053] When the measurement light has absorption wavelengths of a plurality of components, the component concentration measuring unit 201 can calculate the component concentration from the plurality of wavelengths using the following formula (3).

number

[0054] FIG. 5 is a diagram for explaining the detection of transmitted light of the working fluid in a conventional example. The conventional example in FIG. 5 is an example in which the refrigeration cycle device 100 does not have a refrigerant heat exchanger 4 between the condenser 3 and the optical sensor 8. In the conventional example, when the refrigeration cycle device 100 performs low-load operation or the like and the degree of supercooling of the refrigerant at the refrigerant outlet of the condenser 3 becomes small, the refrigerant flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided becomes in a gas-liquid two-phase state. In this case, as shown in FIG. 5, a gas-liquid interface V is formed by the working fluid in the refrigerant pipe 501, and the irradiated light of the optical sensor 8 is reflected, refracted, and scattered at the gas-liquid interface V, and the intensity of the transmitted light detected by the detector 82 decreases.

[0055] Furthermore, what can be measured by optical measurement using optical sensor 8 is the volume ratio of the measurement region. If the fluid speed is constant for a single-phase fluid, the component ratio can be measured as being approximately the same as the volume ratio. On the other hand, in the case of a two-phase fluid, the gas flow rate and the liquid flow rate are different, and the component ratio of the liquid phase is the ratio of (gas component speed x gas component volume + liquid component speed x liquid component volume). Since it is generally difficult to measure the gas flow rate and the liquid flow rate, when the working fluid flowing through refrigerant pipe 501 is a two-phase fluid, the detection accuracy of detector 82 decreases.

[0056] In contrast, the refrigeration cycle apparatus 100 of the present embodiment is provided with an inter-refrigerant heat exchanger 4 between the condenser 3 and the optical sensor 8, which exchanges heat between the high-temperature refrigerant flowing out from the condenser 3 and a low-temperature refrigerant to convert it into a liquid refrigerant. This ensures that the working fluid flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided is in a liquid state (single-phase state), and therefore a gas-liquid interface V is not formed in the refrigerant pipe 501. As a result, the detection accuracy of the light transmitted through the working fluid by the optical sensor 8 is improved, and the measurement accuracy of the component concentrations of the working fluid is also improved.

[0057] Furthermore, by improving the measurement accuracy of the component concentration of the working fluid, it becomes possible to appropriately perform operation control that reduces the occurrence of dilution of the refrigeration oil in the compressor 1 and suppresses breakdowns, as well as operation control that suppresses frosting and freezing. As a means for suppressing dilution of the refrigeration oil, there is a means for increasing the degree of refrigerant superheat at the inlet of the compressor 1, but in this case, the input of the compressor 1 per capacity increases, making it difficult to achieve both quality and performance improvement. In contrast, in the first embodiment, it is possible to achieve both quality and performance improvement. In particular, when the refrigerant contains R32 refrigerant, the gas density of R32 refrigerant at the same saturation temperature is small, so the saturation temperature change in the two-phase region is large, and the effect of operation control is large.

[0058] Furthermore, the refrigeration cycle apparatus 100 of the present embodiment includes the optical sensor 8 in the same unit (heat source unit 10 in this embodiment) as the unit including the refrigerant heat exchanger 4. This is more effective than the case where the optical sensor 8 is disposed in a unit different from the unit including the refrigerant heat exchanger 4, because it can suppress the working fluid from becoming two-phase gas-liquid due to pressure loss in the refrigerant pipe 501 connecting the units.

[0059] Embodiment 2 <Configuration of refrigeration cycle device> Fig. 6 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100A according to embodiment 2. The refrigeration cycle apparatus 100A according to embodiment 2 is a hot water supply apparatus that supplies hot water or a hot water heating apparatus that performs heating using hot water. In Fig. 6, solid arrows indicate the flow of refrigerant, and dashed arrows indicate the flow of water. For simplification, Fig. 6 shows only a part of the water circuit 300.

[0060] 6, the refrigeration cycle apparatus 100A includes a heat source unit 10A and a load unit 20A. The heat source unit 10A and the load unit 20A each have an individual housing, and are installed in different locations, for example, outdoors and indoors.

[0061] The heat source unit 10A includes a compressor 1, a refrigerant heat exchanger 4, a cooling throttling device 40, an optical sensor 8, a first throttling device 51, an evaporator 6, a second fan 61, a refrigerant tank 7, and a control device 200. The load unit 20A includes a condenser 3A and a pump 32.

[0062] The configurations and functions of the compressor 1, refrigerant heat exchanger 4, cooling throttling device 40, first throttling device 51, evaporator 6, second fan 61, refrigerant tank 7, optical sensor 8, and control device 200 in the heat source unit 10A are the same as those in embodiment 1.

[0063] The condenser 3A in the load unit 20A is a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-tube heat exchanger, or a plate heat exchanger that performs heat exchange between the refrigerant flowing through the refrigerant circuit and the water flowing through the water circuit 300.

[0064] The pump 32 circulates the water flowing through the water circuit 300. The pump 32 includes an inverter circuit (not shown), and can change the water flow rate when transporting water by changing the drive rotation speed according to an instruction from the control device 200.

[0065] <Operation of the refrigeration cycle device> Next, the operation of the refrigeration cycle apparatus 100A will be described together with the flow of the refrigerant. When the compressor 1 of the refrigeration cycle apparatus 100A is driven, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the condenser 3A.

[0066] In the condenser 3A, heat exchange occurs between the high-temperature, high-pressure gas refrigerant that has flowed into the condenser 3A and the water flowing through the water circuit 300. The refrigerant that has undergone heat exchange in the condenser 3A is condensed to become a high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. In the condenser 3A, the water heated by heat exchange with the refrigerant is used for hot water supply or hot water heating.

[0067] The high-pressure liquid refrigerant or gas-liquid two-phase refrigerant flowing out of the condenser 3A flows into a condensed fluid flow passage 41 of the refrigerant heat exchanger 4. The flow of the refrigerant after the refrigerant heat exchanger 4 is the same as in the first embodiment.

[0068] As described above, in the refrigeration cycle apparatus 100A of the present embodiment, the refrigerant-to-refrigerant heat exchanger 4 that converts the high-temperature refrigerant flowing out from the condenser 3A into a liquid refrigerant by heat exchange with a low-temperature refrigerant is also provided between the condenser 3A and the optical sensor 8. This ensures that the working fluid flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided is in a liquid state, improving the detection accuracy of the light transmitted through the working fluid by the optical sensor 8 and improving the measurement accuracy of the component concentrations of the working fluid.

[0069] Embodiment 3 <Configuration of refrigeration cycle device> Fig. 7 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100B according to embodiment 3. As shown in Fig. 7, the refrigeration cycle apparatus 100B of embodiment 3 differs from embodiment 1 in that a heat source unit 10B includes a second throttling device 52. The other configurations are the same as those of embodiment 1.

[0070] The second throttling device 52 is provided between the condenser 3 and the refrigerant heat exchanger 4, and expands the refrigerant flowing out from the condenser 3 to reduce its pressure. The second throttling device 52 is, for example, an electronic expansion valve whose opening degree can be controlled. Note that the second throttling device 52 is not limited to an electronic expansion valve, and may be a mechanical expansion valve employing a diaphragm in a pressure receiving section, a capillary tube, or the like.

[0071] The opening degree of the second throttling device 52 is controlled by the operation control unit 202 of the control device 200. By controlling the opening degree of the second throttling device 52, the pressure of the working fluid flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided can be controlled.

[0072] The light absorption characteristics depend on the pressure and temperature of the working fluid, but the pressure of the working fluid changes depending on the operation of the refrigeration cycle apparatus 100B. Therefore, the operation control unit 202 controls the aperture of the second throttling device 52 depending on the operation of the refrigeration cycle apparatus 100B. In this case, a pressure sensor (not shown) that measures the pressure of the working fluid flowing through the refrigerant pipe 501 is provided in the refrigerant pipe 501, and the operation control unit 202 controls the aperture of the second throttling device 52 so that the measurement value of the pressure sensor falls within an allowable range. The allowable range is a range in which detection failure of the optical sensor 8 does not occur.

[0073] For example, when the opening degree of the second throttling device 52 becomes small, the refrigerant flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided may enter a gas-liquid two-phase state due to the pressure loss of the second throttling device 52. Fig. 8 is a Mollier diagram when the refrigerant flowing through the refrigerant pipe 501 enters a gas-liquid two-phase state due to the pressure loss of the second throttling device 52. In this case, a gas-liquid interface V is formed in the refrigerant pipe 501 as in the conventional example shown in Fig. 5, which reduces the detection accuracy of the transmitted light by the optical sensor 8 and causes detection failure.

[0074] Therefore, when a detection failure occurs in the optical sensor 8, the component concentration measuring unit 201 of the control device 200 notifies the operation control unit 202 of the occurrence of the detection failure. When the operation control unit 202 is notified of the occurrence of the detection failure in the optical sensor 8, it reduces the opening degree of the first throttling device 51 and increases the opening degree of the second throttling device 52.

[0075] Fig. 9 is a Mollier diagram of the refrigeration cycle apparatus 100B according to embodiment 3. By controlling the opening degrees of the first throttling device 51 and the second throttling device 52 as described above, it is possible to increase the temperature difference between the high-temperature refrigerant and the low-temperature refrigerant in the refrigerant-to-refrigerant heat exchanger 4, and promote the cooling of the high-temperature refrigerant. As a result, the refrigerant flowing through the refrigerant pipe 501 can be made into a liquid state, as shown in the Mollier diagram in Fig. 9.

[0076] This ensures that the working fluid flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided is in a liquid state, and therefore a gas-liquid interface V is not formed in the refrigerant pipe 501. As a result, the detection accuracy of the light transmitted through the working fluid by the optical sensor 8 is improved, and the measurement accuracy of the component concentrations of the working fluid is also improved.

[0077] Embodiment 4 <Configuration of refrigeration cycle device> 10 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100C according to embodiment 4. The refrigeration cycle apparatus 100C according to embodiment 3 is an air conditioner that cools and heats a space to be air-conditioned.

[0078] As shown in FIG. 10, the refrigeration cycle apparatus 100C includes a heat source unit 10C and a load unit 20C. The heat source unit 10C is an outdoor unit of an air conditioner, and the load unit 20C is an indoor unit of the air conditioner. The heat source unit 10C includes a compressor 1, a flow path switching valve 2, an outdoor heat exchanger 30, a first fan 31, a second throttling device 52, a flow path switching mechanism 9, a refrigerant-to-refrigerant heat exchanger 4, a cooling throttling device 40, an optical sensor 8, a refrigerant tank 7, and a control device 200. The load unit 20C includes a first throttling device 51, an indoor heat exchanger 60, and a second fan 61.

[0079] The configurations and functions of the compressor 1, the first fan 31, the refrigerant heat exchanger 4, the cooling throttling device 40, the optical sensor 8, the refrigerant tank 7, and the control device 200 in the heat source unit 10C are the same as those in the first embodiment. The configurations and functions of the first throttling device 51 and the second fan 61 in the load unit 20C are the same as those in the first embodiment.

[0080] The flow path switching valve 2 is, for example, a four-way valve, and switches the flow path of the refrigerant discharged from the compressor 1. The control device 200 performs heating operation or cooling operation by switching the state of the flow path switching valve 2. Specifically, during cooling operation, the flow path switching valve 2 switches the flow of the refrigerant so as to connect the discharge port of the compressor 1 to the refrigerant inlet of the outdoor heat exchanger 30 and to connect the suction port of the compressor 1 to the refrigerant outlet of the indoor heat exchanger 60. Also, during heating operation, the flow path switching valve 2 switches the flow of the refrigerant so as to connect the discharge port of the compressor 1 to the refrigerant inlet of the indoor heat exchanger 60 and to connect the suction port of the compressor 1 to the refrigerant outlet of the outdoor heat exchanger 30.

[0081] The outdoor heat exchanger 30 functions as an evaporator during heating operation, exchanging heat between the refrigerant that has flowed inside and the outdoor air, and evaporating and vaporizing the refrigerant. The outdoor heat exchanger 30 functions as a condenser during cooling operation, exchanging heat between the refrigerant that has flowed inside and the outdoor air, and condensing and liquefying the refrigerant. In order to increase the efficiency of heat exchange between the refrigerant and the air in the outdoor heat exchanger 30, a first fan 31 is disposed adjacent to the outdoor heat exchanger 30.

[0082] The indoor heat exchanger 60 functions as a condenser during heating operation, exchanging heat between the refrigerant that has flowed inside and the indoor air, condensing and liquefying the refrigerant. The indoor heat exchanger 60 functions as an evaporator during cooling operation, exchanging heat between the refrigerant that has flowed inside and the air, evaporating and vaporizing the refrigerant. In order to increase the efficiency of heat exchange between the refrigerant and the air in the indoor heat exchanger 60, a second fan 61 is disposed adjacent to the indoor heat exchanger 60.

[0083] The outdoor heat exchanger 30 and the indoor heat exchanger 60 are, for example, a fin-and-tube heat exchanger or a microchannel heat exchanger. Note that the outdoor heat exchanger 30 and the indoor heat exchanger 60 may also be a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-pipe heat exchanger, a plate heat exchanger, or the like that exchanges heat between a heat medium such as water or brine and a refrigerant.

[0084] The second throttling device 52 expands the refrigerant flowing out from the outdoor heat exchanger 30 to reduce the pressure. The second throttling device 52 is, for example, an electronic expansion valve whose opening degree can be controlled. Note that the second throttling device 52 is not limited to an electronic expansion valve, and may be a mechanical expansion valve employing a diaphragm in a pressure receiving section, a capillary tube, or the like. The opening degree of the second throttling device 52 is controlled by the operation control unit 202 of the control device 200.

[0085] The flow path switching mechanism 9 switches the flow of the refrigerant so that the refrigerant heat exchanger 4 is located between the heat exchanger functioning as a condenser and the optical sensor 8, whether the refrigeration cycle apparatus 100C is performing cooling operation or heating operation. The flow path switching mechanism 9 in this embodiment is composed of a first check valve 91, a second check valve 92, a third check valve 93, and a fourth check valve 94.

[0086] The first check valve 91 is provided in the refrigerant pipe 504 that connects the outdoor heat exchanger 30 and the refrigerant inlet of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. The first check valve 91 allows the flow of refrigerant from the outdoor heat exchanger 30 to the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4, and blocks the flow of refrigerant from the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 to the outdoor heat exchanger 30.

[0087] The second check valve 92 is provided between the optical sensor 8 and the first throttling device 51 of the refrigerant pipe 501. The second check valve 92 allows the flow of refrigerant from the optical sensor 8 to the first throttling device 51 and blocks the flow of refrigerant from the first throttling device 51 to the optical sensor 8.

[0088] The third check valve 93 is provided in a refrigerant pipe 505 that connects the first throttling device 51 and the refrigerant inlet of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. The third check valve 93 allows the flow of refrigerant from the first throttling device 51 to the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4, and blocks the flow of refrigerant from the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 to the first throttling device 51.

[0089] The fourth check valve 94 is provided in a branch pipe 506 that branches off from between the optical sensor 8 and the second check valve 92 of the refrigerant pipe 501 and is connected to between the outdoor heat exchanger 30 and the first check valve 91 of the refrigerant pipe 504. The fourth check valve 94 allows the flow of refrigerant from the optical sensor 8 to the outdoor heat exchanger 30 and blocks the flow of refrigerant from the outdoor heat exchanger 30 to the optical sensor 8.

[0090] <Operation of the refrigeration cycle device> Next, the operation of the refrigeration cycle apparatus 100C will be described together with the flow of the refrigerant. FIG. 11 is a diagram for explaining the flow of the refrigerant during cooling operation of the refrigeration cycle apparatus 100C according to the fourth embodiment. In FIG. 11, some of the flow paths in the refrigerant circuit diagram in FIG. 10 are omitted for ease of viewing. The solid arrows in FIG. 11 indicate the flow of the refrigerant. Furthermore, during cooling operation, the control device 200 fully opens the second throttling device 52. Therefore, the second throttling device 52 is not shown in FIG. 11.

[0091] When the compressor 1 of the refrigeration cycle apparatus 100 is driven, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 30 through the flow path switching valve 2. The outdoor heat exchanger 30 functions as a condenser, and heat is exchanged between the high-temperature, high-pressure gas refrigerant that has flowed inside and air supplied by the first fan 31. The refrigerant that has undergone heat exchange in the outdoor heat exchanger 30 is condensed to become a high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant.

[0092] The high-temperature, high-pressure liquid refrigerant or gas-liquid two-phase refrigerant flowing out of the outdoor heat exchanger 30 passes through the first check valve 91 and flows into the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the low-pressure passage 42 of the inter-refrigerant heat exchanger 4, is cooled, and becomes liquid refrigerant. Then, the refrigerant flows out of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4.

[0093] The liquid refrigerant flowing out from the condensed fluid flow path 41 of the refrigerant heat exchanger 4 flows through the refrigerant pipe 501, and a part of it is diverted to the branch pipe 502. The liquid refrigerant flowing through the refrigerant pipe 501 passes through the optical sensor 8. The liquid refrigerant that has passed through the optical sensor 8 passes through the second check valve 92 and is depressurized by the first throttling device 51, becoming in a low-pressure gas-liquid two-phase state, and flows into the indoor heat exchanger 60.

[0094] The indoor heat exchanger 60 functions as an evaporator, and heat is exchanged between the refrigerant in a gas-liquid two-phase state that has flowed into the indoor heat exchanger 60 and the air supplied by the second fan 61, and the liquid refrigerant in the gas-liquid two-phase state evaporates to become a low-pressure gas refrigerant. The air cooled by this heat exchange is supplied to the space to be air-conditioned, and the space to be air-conditioned is cooled.

[0095] On the other hand, the refrigerant branched to the branch pipe 502 is decompressed by the cooling throttle device 40 to become a medium-pressure liquid refrigerant or a gas-liquid two-phase refrigerant mainly composed of liquid, and flows into the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the condensed fluid flow path 41 to become a gas-liquid two-phase refrigerant or a low-pressure gas refrigerant, and flows out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The low-pressure gas-liquid two-phase refrigerant or gas refrigerant flowing out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 flows through the refrigerant pipe 503, and merges with the low-pressure gas refrigerant flowing out of the indoor heat exchanger 60.

[0096] The low-pressure gas refrigerant flowing out from the indoor heat exchanger 60 merges with the refrigerant flowing out from the low-pressure flow path 42 of the refrigerant-to-refrigerant heat exchanger 4, and flows into the refrigerant tank 7. Thereafter, the gas refrigerant separated in the refrigerant tank 7 is sucked into the compressor 1, compressed again by the compressor 1, and discharged.

[0097] Fig. 12 is a diagram for explaining the flow of refrigerant during heating operation of the refrigeration cycle apparatus 100C according to embodiment 4. In Fig. 12, some flow paths of the refrigerant circuit diagram in Fig. 10 are omitted for ease of viewing. Solid arrows in Fig. 12 indicate the flow of refrigerant. Furthermore, during heating operation, the control device 200 fully opens the first throttling device 51. Therefore, the first throttling device 51 is not shown in Fig. 12.

[0098] When the compressor 1 of the refrigeration cycle apparatus 100C is driven, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the indoor heat exchanger 60 through the flow path switching valve 2. The indoor heat exchanger 60 functions as a condenser, and heat is exchanged between the high-temperature, high-pressure gas refrigerant that has flowed inside and air supplied by the second fan 61. The refrigerant that has undergone heat exchange in the indoor heat exchanger 60 is condensed to become a high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. The air heated by this heat exchange is supplied to the space to be air-conditioned, and the space to be air-conditioned is heated.

[0099] The high-temperature, high-pressure liquid refrigerant or gas-liquid two-phase refrigerant flowing out of the indoor heat exchanger 60 passes through the refrigerant pipe 505 and the third check valve 93 and flows into the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the low-pressure passage 42 of the inter-refrigerant heat exchanger 4, is cooled, and becomes liquid refrigerant. Then, the refrigerant flows out of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4.

[0100] The liquid refrigerant flowing out from the condensed fluid flow path 41 of the refrigerant heat exchanger 4 flows through the refrigerant pipe 501, and a part of it is diverted to the branch pipe 502. The liquid refrigerant flowing through the refrigerant pipe 501 passes through the optical sensor 8. The liquid refrigerant that has passed through the optical sensor 8 passes through the branch pipe 506 and the fourth check valve 94, is depressurized by the second throttling device 52, becomes a low-pressure gas-liquid two-phase state, and flows into the outdoor heat exchanger 30.

[0101] The outdoor heat exchanger 30 functions as an evaporator, and heat is exchanged between the two-phase gas-liquid refrigerant that flows into the outdoor heat exchanger 30 and the air supplied by the first fan 31, and the liquid refrigerant in the two-phase gas-liquid refrigerant evaporates to become a low-pressure gas refrigerant.

[0102] On the other hand, the refrigerant branched to the branch pipe 502 is decompressed by the cooling throttle device 40 to become a medium-pressure liquid refrigerant or a gas-liquid two-phase refrigerant mainly composed of liquid, and flows into the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the condensed fluid flow path 41 to become a gas-liquid two-phase refrigerant or a low-pressure gas refrigerant, and flows out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The low-pressure gas-liquid two-phase refrigerant or gas refrigerant flowing out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 flows through the refrigerant pipe 503, and merges with the low-pressure gas refrigerant flowing out of the outdoor heat exchanger 30.

[0103] The low-pressure gas refrigerant flowing out from the outdoor heat exchanger 30 merges with the refrigerant flowing out from the low-pressure flow path 42 of the refrigerant-to-refrigerant heat exchanger 4, and flows into the refrigerant tank 7. Thereafter, the gas refrigerant separated in the refrigerant tank 7 is sucked into the compressor 1, compressed again by the compressor 1, and discharged.

[0104] As described above, in the refrigeration cycle apparatus 100C of the present embodiment, the refrigerant heat exchanger 4 is also provided between the heat exchanger functioning as a condenser and the optical sensor 8 during both cooling and heating operations. Therefore, similarly to the first embodiment, it is possible to improve the measurement accuracy of the component concentrations of the working fluid in the refrigeration cycle apparatus 100C.

[0105] The flow path switching mechanism 9 is not limited to a configuration including four check valves. The flow path switching mechanism 9 may be configured, for example, as a four-way valve, as long as it switches the refrigerant flow path so that the optical sensor 8 is located downstream of the condensed fluid flow path 41 of the refrigerant-to-refrigerant heat exchanger 4 in both cooling and heating operations.

[0106] Embodiment 5. <Configuration of refrigeration cycle device> 13 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100D according to embodiment 5. The refrigeration cycle apparatus 100D of the present embodiment is an air conditioner that cools and heats a plurality of spaces to be air-conditioned.

[0107] 13, a refrigeration cycle apparatus 100D of the fifth embodiment includes a heat source unit 10D, a relay unit 15, and a plurality of load units 21D and 22D. The heat source unit 10D, the relay unit 15, and the plurality of load units 21D and 22D each have an individual housing, and are installed in different locations, for example, outdoors and indoors.

[0108] The heat source unit 10D includes a compressor 1, a first condenser 3B, a first fan 31, and a refrigerant tank 7. The relay unit 15 includes a refrigerant heat exchanger 4, a cooling throttling device 40, an optical sensor 8, a control device 200, a branching section 45, and a third throttling device 53. The load unit 21D includes a first throttling device 51, an evaporator 6, and a second fan 61. The load unit 22D includes a second condenser 3C, a fourth throttling device 54, and a first fan 31.

[0109] The compressor 1, refrigerant heat exchanger 4, cooling throttling device 40, first throttling device 51, evaporator 6, second fan 61, refrigerant tank 7, optical sensor 8, and control device 200 of the refrigeration cycle apparatus 100D have the same configurations and functions as those of the first embodiment. The first condenser 3B and the second condenser 3C have the same configurations and functions as the condenser 3 of the first embodiment.

[0110] The branching unit 45 branches the refrigerant that has flowed in to the load unit 21D and the load unit 22D. The branching unit 45 is, for example, a gas-liquid separator, and is connected to the load units 21D and 22D so as to cause the refrigerant that contains a large amount of gas phase to flow into the second condenser 3C of the load unit 22D and the refrigerant that contains a large amount of liquid phase to flow into the evaporator 6 of the load unit 21D.

[0111] The third throttling device 53 expands the refrigerant flowing out from the branching portion 45 to reduce the pressure. The fourth throttling device 54 expands the refrigerant flowing out from the second condenser 3C to reduce the pressure. The third throttling device 53 and the fourth throttling device 54 are, for example, electronic expansion valves whose opening degree can be controlled. Note that the third throttling device 53 and the fourth throttling device 54 are not limited to electronic expansion valves, and may be mechanical expansion valves using a diaphragm in the pressure receiving portion, or capillary tubes, etc. The opening degrees of the third throttling device 53 and the fourth throttling device 54 are controlled by the operation control unit 202 of the control device 200.

[0112] <Operation of the refrigeration cycle device> Next, the operation of the refrigeration cycle apparatus 100D will be described together with the flow of the refrigerant. The solid arrows in Fig. 13 indicate the flow of the refrigerant. When the compressor 1 of the refrigeration cycle apparatus 100D is driven, a high-temperature, high-pressure gas refrigerant is discharged from the compressor 1. The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 flows into the first condenser 3B.

[0113] In the first condenser 3B, heat exchange occurs between the high-temperature, high-pressure gas refrigerant that has flowed into the first condenser 3B and air supplied by the first fan 31. The refrigerant that has undergone heat exchange in the first condenser 3B condenses and becomes a high-temperature, high-pressure gas-liquid two-phase refrigerant.

[0114] The high-temperature, high-pressure two-phase gas-liquid refrigerant flowing out from the first condenser 3B flows into the branching section 45. The two-phase gas-liquid refrigerant flowing into the branching section 45 is separated into a gas refrigerant and a liquid refrigerant, and the gas refrigerant flows into the second condenser 3C. In the second condenser 3C, heat exchange occurs between the high-temperature, high-pressure gas refrigerant that has flowed into the inside of the second condenser 3C and the air supplied by the first fan 31. The refrigerant that has undergone heat exchange in the second condenser 3C is condensed to become a high-temperature, high-pressure liquid refrigerant. The air heated by this heat exchange is supplied to the air-conditioned space in which the load unit 22D is provided, and the air-conditioned space is heated.

[0115] The high-temperature, high-pressure liquid refrigerant flowing out of the second condenser 3C is depressurized by the fourth throttling device 54, and flows into the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the low-pressure passage 42 of the inter-refrigerant heat exchanger 4, is cooled, and becomes liquid refrigerant. The refrigerant then flows out of the condensed fluid passage 41 of the inter-refrigerant heat exchanger 4.

[0116] The liquid refrigerant flowing out from the condensed fluid flow path 41 of the refrigerant-to-refrigerant heat exchanger 4 merges with the liquid refrigerant flowing out from the branching portion 45 and depressurized by the third throttling device 53, flows through the refrigerant pipe 501, and a part of it is diverted to the branch pipe 502. The liquid refrigerant flowing through the refrigerant pipe 501 passes through the optical sensor 8. The liquid refrigerant that has passed through the optical sensor 8 is depressurized by the first throttling device 51, becomes a low-pressure gas-liquid two-phase state, and flows into the evaporator 6.

[0117] In the evaporator 6, heat exchange takes place between the refrigerant in a gas-liquid two-phase state that has flowed into the evaporator 6 and the air supplied by the second fan 61, and the liquid refrigerant in the gas-liquid two-phase state refrigerant evaporates to become a low-pressure gas refrigerant. The air cooled by this heat exchange is supplied to the space to be air-conditioned in which the load unit 21D is provided, and the space to be air-conditioned is cooled.

[0118] On the other hand, the refrigerant branched to the branch pipe 502 is decompressed by the cooling throttle device 40 to become a medium-pressure liquid refrigerant or a gas-liquid two-phase refrigerant mainly composed of liquid, and flows into the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The refrigerant flowing through the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 exchanges heat with the refrigerant flowing through the condensed fluid flow path 41 to become a gas-liquid two-phase refrigerant or a low-pressure gas refrigerant, and flows out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4. The low-pressure gas-liquid two-phase refrigerant or gas refrigerant flowing out of the low-pressure flow path 42 of the inter-refrigerant heat exchanger 4 flows through the refrigerant pipe 503, and merges with the low-pressure gas refrigerant flowing out from the evaporator 6.

[0119] The low-pressure gas refrigerant flowing out from the evaporator 6 joins with the refrigerant flowing out from the low-pressure flow path 42 of the refrigerant-to-refrigerant heat exchanger 4, and flows into the refrigerant tank 7. Thereafter, the gas refrigerant separated in the refrigerant tank 7 is sucked into the compressor 1, compressed again by the compressor 1, and discharged. In the refrigeration cycle apparatus 100, this cycle is repeated.

[0120] Like the refrigeration cycle apparatus 100D of the present embodiment, when the optical sensor 8 is mounted on the relay unit 15, the measurement accuracy of the component concentration of the working fluid in the refrigeration cycle apparatus 100D can be improved, similarly to the first embodiment. That is, the optical sensor 8 may be provided between the refrigerant outlet of the condensed fluid passage 41 of the refrigerant-to-refrigerant heat exchanger 4 and the first throttling device 51, and the unit to which it is mounted is not limited.

[0121] Furthermore, by configuring the refrigeration cycle device 100D, it is possible to measure the component concentration of the working fluid flowing through a heat exchanger operating as an evaporator, even when evaporators and condensers are mixed in the heat exchangers installed in multiple heat load units.

[0122] Furthermore, in the case where the refrigeration cycle apparatus 100D includes a plurality of condensers as in the present embodiment, an excess of refrigerant is generated, and the inlet superheat of the compressor 1 becomes smaller or a gas-liquid two-phase state occurs, compared to the case where the number of condensers is one. In this case as well, an optical sensor 8 is disposed between the condenser and the first throttling device, and the operation is controlled by measuring the component concentrations of the working fluid, thereby achieving both quality and performance improvement.

[0123] The number of optical sensors 8 and refrigerant heat exchangers 4 included in the refrigeration cycle apparatus 100D may be two or more. The number of load units 21D and the number of load units 22D included in the refrigeration cycle apparatus 100D are not limited to the example in FIG. 13, and may be more than one.

[0124] Although the embodiment has been described above, the present disclosure is not limited to the above embodiment, and various modifications and combinations are possible without departing from the spirit of the present disclosure. Modifications of the present disclosure will be described below.

[0125] Variation 1. Fig. 14 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100E according to Modification 1. As shown in Fig. 14, a refrigerant inlet of a low-pressure flow path 42 of a refrigerant heat exchanger 4A may be connected to a refrigerant outlet of an evaporator 6, and a refrigerant outlet of the low-pressure flow path 42 may be connected to a refrigerant tank 7 via a refrigerant pipe 503. In this case, the branch pipe 502 and the cooling throttle device 40 may be omitted.

[0126] Even in the case of the configuration of this modified example, the refrigerant flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided can be made into a liquid state, and the same effects as those of the first embodiment can be obtained.

[0127] Variation 2. Fig. 15 is a schematic diagram showing an installation direction of optical sensor 8 in a refrigeration cycle apparatus according to Modification 2. As shown in Fig. 15, optical sensor 8 of this modification is attached to refrigerant pipe 501 so that acute angle θ1 between the direction of light irradiated from irradiator 81 and a plane perpendicular to the direction of gravity is smaller than 45°. More desirably, optical sensor 8 is attached to refrigerant pipe 501 so that acute angle θ1 between the direction of light irradiated from irradiator 81 and a plane perpendicular to the direction of gravity is smaller than 30°.

[0128] When the acute angle θ1 between the direction of light irradiated from the irradiator 81 of the optical sensor 8 and the plane perpendicular to the direction of gravity is greater than 45° and the direction of the irradiated light approaches the direction of gravity, the working fluid at the irradiated surface separates due to density difference. FIG. 16 is a diagram for explaining the state of the working fluid at a low flow rate. When the speed of the working fluid flowing through the refrigerant pipe 501 is low, a density difference occurs between the components of the working fluid flowing through the refrigerant pipe 501 as shown in FIG. 16, and a liquid-liquid level L is formed. When the working fluid is biased as shown in FIG. 16, a deviation occurs between the line ratio of the composition on the light beam and the volume ratio of the fluid. In the case of FIG. 16, a large amount of heavy components are detected in the working fluid. In contrast, by installing the optical sensor 8 as in this modified example, the decrease in detection accuracy of the transmitted light due to separation caused by density difference is suppressed, and the measurement accuracy of the component concentration of the working fluid is improved. Although FIG. 15 shows a case where the acute angle between the extension direction of refrigerant pipe 501 and the direction of gravity is smaller than 45°, the acute angle between the extension direction of refrigerant pipe 501 and the direction of gravity may be larger than 45°.

[0129] Variation 3. Fig. 17 is a schematic diagram showing an installation direction of an optical sensor 8 of a refrigeration cycle apparatus according to Modification 3. As shown in Fig. 17, the refrigerant pipe 501 on which the optical sensor 8 of this modification is installed is installed so that the acute angle θ2 between the extension direction of the refrigerant pipe 501 and the direction of gravity is smaller than 45°. More preferably, the refrigerant pipe 501 on which the optical sensor 8 is installed is installed so that the acute angle θ2 between the extension direction of the refrigerant pipe 501 and the direction of gravity is smaller than 30°.

[0130] With the configuration of this modification, the angle between the flow direction of the refrigerant in the refrigerant pipe 501 and the direction of gravity becomes smaller, and the component of the refrigerant flow in the direction of gravity becomes larger. This makes it possible to suppress separation due to differences in density of the refrigerant and ensure symmetry of the component distribution in the cross-sectional direction of the flow path. As a result, deterioration in the detection accuracy of the transmitted light is suppressed, and the measurement accuracy of the component concentration of the working fluid is improved. In particular, even when the flow velocity of the refrigerant is low, the detection accuracy of the transmitted light and the measurement accuracy of the component concentration are improved.

[0131] Variation 4. FIG. 18 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100F according to the fourth modification. It has been found by tests that the absorbance measured by the optical sensor 8 is highly sensitive to the temperature or pressure of the working fluid. Therefore, as shown in FIG. 18, a temperature sensor 801 and a pressure sensor 802 may be provided in the refrigerant pipe 501 of the refrigeration cycle apparatus 100F to measure the temperature and pressure of the working fluid flowing through the refrigerant pipe 501. Then, the component concentration measuring unit 201 of the control device 200 may correct the component concentration using the measured temperature and pressure and a table including preset correction values. The temperature sensor 801 and the pressure sensor 802 are installed in the same unit as the optical sensor 8, thereby eliminating the influence of the pressure loss of the refrigerant heat exchanger 4 or the pressure loss of the refrigerant pipe 501 between the units.

[0132] In addition, when a non-azeotropic refrigerant is used as the working fluid of the refrigeration cycle apparatus 100, the circulating composition ratio of the working fluid changes significantly due to refrigerant leakage during refrigerant charging at the time of installation, or the amount of refrigerant held in the refrigerant tank 7 that changes depending on operation. In order to realize appropriate control of the refrigeration cycle apparatus 100, the composition ratio of the working fluid may be predicted and the frequency of the compressor 1 or the opening degree of the first throttling device 51 may be controlled. In this case, a model that has been learned in advance based on the absorbance, temperature, and pressure of the components contained in the working fluid is stored in the storage unit 203 of the control device 200. Then, the control device 200 may output the circulating composition ratio of the working fluid using the learning model, using the absorbance, refrigerant temperature, and refrigerant pressure measured by the optical sensor 8, the temperature sensor 801, and the pressure sensor 802 as inputs.

[0133] In this case, when the refrigerant pressure measured by the pressure sensor 802 is higher than the learning range of the learning model and the measurement accuracy of the component concentration decreases, the control device 200 decreases the opening of the second throttling device 52. Also, when the refrigerant pressure measured by the pressure sensor 802 is lower than the learning range of the learning model and the measurement accuracy of the component concentration decreases, the control device 200 increases the opening of the second throttling device 52. This improves the measurement accuracy of the component concentration. The threshold value used to determine whether to change the opening of the second throttling device 52 is a design value set based on the pressure range of the learning model.

[0134] Variation 5. 19 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100G according to Modification 5. The refrigeration cycle apparatus 100G of Modification 5 includes a heat source unit 10G, a load unit 21G, and a load unit 22G. The heat source unit 10G includes a compressor 1, a flow path switching valve 2, an outdoor heat exchanger 30, a first fan 31, a first throttling device 51, a refrigerant-to-refrigerant heat exchanger 4, a cooling throttling device 40, an optical sensor 8, a refrigerant tank 7, and a control device 200. The load unit 21G and the load unit 22G each include an indoor heat exchanger 60G and a second fan 61.

[0135] In the case where the refrigeration cycle apparatus 100G of this modified example is capable of switching between cooling operation and heating operation and is equipped with multiple load units, in the cooling operation or heating operation in which the number of condensers is greater, an optical sensor 8 may be provided between the condenser and the throttling device provided downstream of the condenser.

[0136] In the configuration of FIG. 19, the heat exchangers that function as condensers in heating operation are two indoor heat exchangers 60G, and the heat exchanger that functions as a condenser in cooling operation is one outdoor heat exchanger 30. That is, the number of condensers in heating operation is greater than the number of condensers in cooling operation. Therefore, an inter-refrigerant heat exchanger 4 is provided between the first throttling device 51 provided downstream of the indoor heat exchanger 60G that serves as a condenser in heating operation and the indoor heat exchanger 60G, and an optical sensor 8 is provided downstream of the inter-refrigerant heat exchanger 4. Note that the effect is not affected even if another throttling device is provided between the inter-refrigerant heat exchanger 4 and the condenser.

[0137] In an operation with a larger number of condensers, excess refrigerant is generated, and the inlet superheat of the compressor 1 is smaller, or the refrigerant is more likely to be in a gas-liquid two-phase state, compared to an operation with a smaller number of condensers. The refrigeration cycle device 100G, which can switch between cooling and heating operations, generally designs the amount of refrigerant for an operation that requires a larger amount of refrigerant. As shown in FIG. 19, in an apparatus that connects one heat source unit and multiple load units, in cooling operation with a larger number of evaporators, the refrigerant connecting the heat source unit and the heat load unit becomes liquid refrigerant, and the required amount of refrigerant increases. Therefore, the amount of refrigerant is designed based on the cooling operation, and in heating operation with a larger number of condensers, excess refrigerant is generated and stored in the refrigerant tank 7, etc. At this time, a large amount of refrigerant oil or high-boiling point components of non-azeotropic refrigerant mixture is stored in the refrigerant tank 7, and the refrigerant oil or refrigerant composition in the refrigerant flowing in the circuit outside the refrigerant tank 7 becomes unclear, which is likely to lead to a decrease in performance or a malfunction. Therefore, since there are significant issues when operating with a large number of condensers as in this modified example, the effect of applying the present disclosure is enhanced by ensuring that the working fluid flowing through the refrigerant pipe 501 in which the optical sensor 8 is provided is in a liquid state (single-phase state) when operating with a large number of condensers.

[0138] Variation 6. Fig. 20 is a refrigerant circuit diagram of a refrigeration cycle apparatus 100H according to Modification 6. Modification 6 is a modification of the fifth embodiment. As shown in Fig. 20, the refrigeration cycle apparatus 100H is obtained by omitting the branching section 45, the third throttling device 53, and the fourth throttling device 54 from the refrigeration cycle apparatus 100D of the fifth embodiment. In this case as well, the same effects as those of the fifth embodiment can be obtained.

[0139] As another modification, in the above embodiment, the control device 200 is configured to include a component concentration measuring unit, but the optical sensor 8 may include a control device and a component concentration measuring unit. In this case, the optical sensor 8 measures the component concentration of the working fluid from the detected transmitted light, and the measured component concentration is transmitted to the operation control unit 202 of the control device 200.

[0140] In addition, each embodiment and each modification can be combined in any desired manner. For example, the second throttling device 52 of embodiment 3 may be provided in the configuration of embodiment 2, embodiment 5, modification 5, or modification 6. In embodiments 1 to 5, modification 5, or modification 6, the learning model of modification 4 may be used to output the circulating composition ratio of the working fluid, etc. [Explanation of symbols]

[0141] 1 compressor, 2 flow path switching valve, 3, 3A condenser, 3B first condenser, 3C second condenser, 4, 4A refrigerant heat exchanger, 6 evaporator, 7 refrigerant tank, 8 optical sensor, 9 flow path switching mechanism, 10, 10A, 10B, 10C, 10D, 10G heat source unit, 15 relay unit, 20, 20A, 20C, 21D, 21G, 22D, 22G load unit, 30 outdoor heat exchanger, 31 first fan, 32 pump, 40 cooling throttle device, 41 condensed fluid flow path, 42 low pressure flow path, 45 branching section, 51 first throttle device, 52 second throttle device, 53 third throttle device, 54 fourth throttle device, 60, 60G indoor heat exchanger, 61 second fan, 80 housing, 81 irradiator, 82 detector, 83 Window plate, 91 first check valve, 92 second check valve, 93 third check valve, 94 fourth check valve, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H refrigeration cycle device, 200 control device, 201 component concentration measurement unit, 202 operation control unit, 203 memory unit, 300 water circuit, 501, 503, 504, 505, refrigerant piping, 501a opening, 502, 506 branch piping, 801 temperature sensor, 802 pressure sensor.

Claims

1. A compressor that compresses and discharges a working fluid; a condenser that condenses the working fluid discharged from the compressor; a refrigerant-to-refrigerant heat exchanger including a condensed fluid flow path through which the working fluid flowing out of the condenser flows, and a low-pressure flow path through which the working fluid flows, the working fluid having a lower pressure than the working fluid flowing through the condensed fluid flow path, and performing heat exchange between the working fluid flowing through the condensed fluid flow path and the working fluid flowing through the low-pressure flow path; a first throttling device that reduces the pressure of the working fluid flowing out of the condensed fluid flow passage of the refrigerant-to-refrigerant heat exchanger; an evaporator that evaporates the working fluid decompressed by the first throttle device; an optical sensor provided in a pipe connecting an outlet of the condensed fluid flow path of the refrigerant-to-refrigerant heat exchanger and the first throttling device, the optical sensor including an illuminator that irradiates light onto the working fluid flowing through the pipe and a detector that detects transmitted light; A control device that measures a concentration of a component contained in the working fluid based on a detection result of the optical sensor; a flow path switching valve that switches a flow path of the working fluid discharged from the compressor; a flow path switching mechanism that switches the flow of the working fluid so that the refrigerant-to-refrigerant heat exchanger is disposed between the condenser and the optical sensor, regardless of the switching of the flow path of the working fluid by the flow path switching valve.

2. A compressor that compresses and discharges a working fluid; a condenser that condenses the working fluid discharged from the compressor; a refrigerant-to-refrigerant heat exchanger including a condensed fluid flow path through which the working fluid flowing out of the condenser flows, and a low-pressure flow path through which the working fluid flows, the working fluid having a lower pressure than the working fluid flowing through the condensed fluid flow path, and performing heat exchange between the working fluid flowing through the condensed fluid flow path and the working fluid flowing through the low-pressure flow path; a first throttling device that reduces the pressure of the working fluid flowing out of the condensed fluid flow passage of the refrigerant-to-refrigerant heat exchanger; an evaporator that evaporates the working fluid decompressed by the first throttle device; an optical sensor provided in a pipe connecting an outlet of the condensed fluid flow path of the refrigerant-to-refrigerant heat exchanger and the first throttling device, the optical sensor including an illuminator that irradiates light onto the working fluid flowing through the pipe and a detector that detects transmitted light; A control device that measures a concentration of a component contained in the working fluid based on a detection result of the optical sensor; a flow path switching valve that switches a flow path of the working fluid discharged from the compressor; A plurality of indoor heat exchangers functioning as the condenser during heating operation and functioning as the evaporator during cooling operation; an outdoor heat exchanger that functions as the evaporator during the heating operation and as the condenser during the cooling operation; The optical sensor is provided in a refrigeration cycle device between the first throttling device and the refrigerant heat exchanger, the first throttling device being provided downstream of the indoor heat exchangers and the outdoor heat exchangers functioning as condensers, in the cooling operation or the heating operation in which the number of indoor heat exchangers and outdoor heat exchangers functioning as condensers is large.

3. A compressor that compresses and discharges a working fluid; a condenser that condenses the working fluid discharged from the compressor; a refrigerant-to-refrigerant heat exchanger including a condensed fluid flow path through which the working fluid flowing out of the condenser flows, and a low-pressure flow path through which the working fluid flows, the working fluid having a lower pressure than the working fluid flowing through the condensed fluid flow path, and performing heat exchange between the working fluid flowing through the condensed fluid flow path and the working fluid flowing through the low-pressure flow path; a first throttling device that reduces the pressure of the working fluid flowing out of the condensed fluid flow passage of the refrigerant-to-refrigerant heat exchanger; an evaporator that evaporates the working fluid decompressed by the first throttle device; an optical sensor provided in a pipe connecting an outlet of the condensed fluid flow path of the refrigerant-to-refrigerant heat exchanger and the first throttling device, the optical sensor including an illuminator that irradiates light onto the working fluid flowing through the pipe and a detector that detects transmitted light; A control device that measures a concentration of a component contained in the working fluid based on a detection result of the optical sensor; a temperature sensor for measuring a temperature of the working fluid flowing through the pipe; a pressure sensor for measuring a pressure of the working fluid flowing through the pipe; The control device includes a storage unit that stores a model learned based on absorbance, temperature, and pressure of the component contained in the working fluid, A refrigeration cycle device that predicts a composition of the working fluid using the model by inputting absorbance, temperature, and pressure measured by the optical sensor, the temperature sensor, and the pressure sensor.

4. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the control device controls an operating frequency of the compressor or an opening degree of the first throttling device based on a concentration of the component contained in the working fluid.

5. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the optical sensor is provided in the same unit as the refrigerant heat exchanger.

6. 6. The refrigeration cycle device according to claim 1, wherein the working fluid is a non-azeotropic mixed refrigerant comprising at least two or more kinds of refrigerants having different boiling points.

7. an inlet of the low-pressure flow path of the refrigerant-to-refrigerant heat exchanger is connected between an outlet of the condensed fluid flow path of the piping and the optical sensor; 7. The refrigeration cycle apparatus according to claim 1, wherein an outlet of the low-pressure flow passage of the refrigerant-to-refrigerant heat exchanger is connected to an outlet of the evaporator.

8. an inlet of the low-pressure flow path of the refrigerant-to-refrigerant heat exchanger is connected to an outlet of the evaporator; 7. The refrigeration cycle apparatus according to claim 1, wherein an outlet of the low-pressure flow passage of the refrigerant-to-refrigerant heat exchanger is connected to a suction port of the compressor.

9. The refrigeration cycle apparatus according to any one of claims 1 to 8, further comprising a second throttling device provided between the condenser and the refrigerant heat exchanger.

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