Refrigeration cycle device

Abstract

To solve a problem that in a refrigeration cycle device that uses a non-azeotropic mixed refrigerant, there is a possibility that a composition of a refrigerant circulating in a refrigerant circuit might be deviated from a base composition and thus heat exchange performance and controllability might deteriorate.SOLUTION: A refrigeration cycle device 100 includes a compressor 21, a utilization side heat exchanger 31, a heat source side expansion valve 25, a heat source side heat exchanger 23, an accumulator 26 and a main refrigerant circuit 10. A non-azeotropic mixed refrigerant is included in the main refrigerant circuit 10. A first value obtained by dividing a value that is obtained by subtracting first amount from second amount by the first amount exceeds a value determined in accordance with the mixed refrigerant. The first amount is the amount of the mixed refrigerant included in the main refrigerant circuit 10. The second amount is the amount of a liquid refrigerant stored in the accumulator 26.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] This relates to a refrigeration cycle device. [Background technology]

[0002] Conventionally, a refrigeration cycle device using a non-azeotropic refrigerant mixture has been known. Patent Document 1 (JP Patent Publication 2015-200431 A) discloses an air conditioner that is a refrigeration cycle device that includes an accumulator connected to the suction side of a compressor and uses a non-azeotropic refrigerant mixture that is a mixture of a low boiling point refrigerant and a high boiling point refrigerant. Summary of the Invention [Problem to be solved by the invention]

[0003] In such a refrigeration cycle device, the excess refrigerant accumulated in the accumulator tends to be a liquid refrigerant containing a large amount of a high boiling point refrigerant, and the circulating refrigerant circulating through the refrigerant circuit of the refrigeration cycle device tends to be a refrigerant containing a large amount of a low boiling point refrigerant, so that the composition of the circulating refrigerant deviates from the base composition of the non-azeotropic refrigerant mixture, which may deteriorate the heat exchange performance and controllability of the refrigeration cycle device. [Means for solving the problem]

[0004] A refrigeration cycle device according to a first aspect includes a compressor, a condenser, an expansion mechanism, an evaporator, an accumulator, and a refrigerant circuit. The compressor, the condenser, the expansion mechanism, the evaporator, and the accumulator are connected in an annular manner in the refrigerant circuit. A mixed refrigerant is sealed in the refrigerant circuit. The mixed refrigerant is a non-azeotropic mixed refrigerant. A first value obtained by subtracting the second amount from the first amount and dividing the result by the first amount exceeds a value determined according to the mixed refrigerant. The first amount is the amount of the mixed refrigerant sealed in the refrigerant circuit. The second amount is the amount of liquid refrigerant stored in the accumulator.

[0005] In the refrigeration cycle device of the first aspect, the amount of liquid refrigerant stored in the accumulator is limited according to the type and amount of refrigerant charged in the refrigerant circuit, thereby preventing the composition of the refrigerant circulating in the refrigerant circuit from deviating from the base composition of the non-azeotropic refrigerant mixture charged in the refrigerant circuit.

[0006] A refrigeration cycle device of a second aspect is the refrigeration cycle device of the first aspect, wherein the second amount is a product of an effective volume of the accumulator and a saturated liquid density of the mixed refrigerant at a pressure of the mixed refrigerant sucked into the compressor.

[0007] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, wherein the mixed refrigerant filled in the refrigerant circuit has a first composition. When liquid refrigerant is stored in the accumulator, the mixed refrigerant circulating through the refrigerant circuit has a second composition. A first value is set so that a second value obtained by subtracting T1 from T3 is 1 K or less. T1 is a saturated liquid temperature of the mixed refrigerant having the first composition. T2 is a target value of the temperature of the mixed refrigerant having the first composition at the outlet of the condenser. T3 is a saturated liquid temperature of the mixed refrigerant having the second composition after the composition of the mixed refrigerant changes from the first composition to the second composition when the temperature of the mixed refrigerant at the outlet of the condenser is controlled to T2.

[0008] In the refrigeration cycle device of the third aspect, the amount of liquid refrigerant stored in the accumulator is set so that the amount of change in temperature glide when the composition of the refrigerant circulating in the refrigerant circuit deviates from the base composition is equal to or less than a predetermined value. The temperature glide is the difference between the saturated gas temperature of the refrigerant and the saturated liquid temperature of the refrigerant. This prevents the composition of the refrigerant circulating in the refrigerant circuit from deviating from the base composition.

[0009] A refrigeration cycle device according to a fourth aspect is the refrigeration cycle device according to any one of the first to third aspects, wherein the mixed refrigerant contains 21.5 mass % of R32 and 78.5 mass % of R1234yf. The first value is greater than 0.65.

[0010] A refrigeration cycle device according to a fifth aspect is the refrigeration cycle device according to any one of the first to third aspects, wherein the mixed refrigerant contains 23.0 mass % of R1132(E) and 77.0 mass % of R1234yf. The first value is greater than 0.15.

[0011] A refrigeration cycle device of a sixth aspect is the refrigeration cycle device of any one of the first to third aspects, wherein the mixed refrigerant contains 22.0 mass % of R1132(E), 56.0 mass % of R1234yf, and 22.0 mass % of R32. The first value is greater than 0.22.

[0012] A refrigeration cycle device of a seventh aspect is the refrigeration cycle device of any one of the first to third aspects, wherein the mixed refrigerant contains 34.0 mass % of R1123 and 66.0 mass % of R1234yf. The first value is greater than 0.12.

[0013] A refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to any one of the first to seventh aspects, further comprising a control unit that controls a parameter relating to the wetness of the mixed refrigerant at the inlet of the accumulator.

[0014] In the refrigeration cycle apparatus of the eighth aspect, for example, by controlling the opening degree of the expansion mechanism, the composition of the refrigerant circulating through the refrigerant circuit is suppressed from deviating from the base composition.

[0015] A refrigeration cycle apparatus according to a ninth aspect is the refrigeration cycle apparatus according to any one of the first to eighth aspects, wherein the accumulator has an effective volume equal to or smaller than a predetermined value.

[0016] In the refrigeration cycle apparatus of the ninth aspect, by setting an upper limit value for the effective volume of the accumulator, deviation of the composition of the refrigerant circulating through the refrigerant circuit from the base composition is suppressed. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing an example of an overall configuration of a refrigeration cycle device 100. FIG. [Diagram 2] FIG. 7 is a block diagram of a control unit 70. [Diagram 3] Mollier diagram of R454C. [Figure 4] FIG. 2 is a vapor-liquid equilibrium diagram of a mixed refrigerant of R32 and R1234yf. [Diagram 5] FIG. 1 is a diagram showing the relationship between the content of R32 and temperature glide for a mixed refrigerant of R32 and R1234yf. [Figure 6] FIG. 1 is a diagram showing the relationship between the refrigerant quality and the R32 content of the circulating refrigerant when R454C is used. [Figure 7] FIG. 13 is a diagram for explaining a decrease in temperature glide. [Figure 8] FIG. 1 is a diagram showing an example of the overall configuration of a refrigeration cycle device 200 that is a testing device for measuring the composition of a circulating refrigerant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (1) Configuration of refrigeration cycle device 100 The refrigeration cycle apparatus 100 is an air conditioner that performs cooling operation and heating operation in a predetermined space to be air-conditioned by a vapor compression refrigeration cycle.

[0019] 1, the refrigeration cycle apparatus 100 mainly includes a heat source unit 2, a utilization unit 3, a liquid side refrigerant connection pipe 6, a gas side refrigerant connection pipe 7, a remote control 8, and a control unit 70. In the refrigeration cycle apparatus 100, the heat source unit 2 and the utilization unit 3 are connected via the liquid side refrigerant connection pipe 6 and the gas side refrigerant connection pipe 7 to configure a main refrigerant circuit 10 in which the refrigerant circulates.

[0020] In the refrigeration cycle apparatus 100, a vapor compression refrigeration cycle is performed in which the refrigerant sealed in the main refrigerant circuit 10 is compressed, condensed, decompressed, evaporated, and then compressed again.

[0021] The refrigeration cycle apparatus 100 may include a plurality of utilization units 3. In this case, a main refrigerant circuit 10 is configured by connecting a plurality of utilization units 3 in parallel to one heat source unit 2.

[0022] The refrigerant sealed in the main refrigerant circuit 10 is a non-azeotropic refrigerant mixture. A non-azeotropic refrigerant mixture is a mixture of multiple types of refrigerants having different boiling points.

[0023] (1-1) Heat source unit 2 The heat source unit 2 is installed outdoors, such as outside a building having a space to be air-conditioned. As shown in Fig. 1, the heat source unit 2 mainly includes a compressor 21, a four-way switching valve 22, a heat source side heat exchanger 23, a heat source side fan 24, a heat source side expansion valve 25, an accumulator 26, a liquid side shutoff valve 28, and a gas side shutoff valve 29.

[0024] The compressor 21 is a device that compresses a low-pressure refrigerant in a refrigeration cycle until it becomes high pressure. The compressor 21 has a sealed structure in which a variable-volume compression element (not shown), such as a rotary type or scroll type, is rotationally driven by a compressor motor 21a. The operating frequency (the rotation speed of the compressor 21) of the compressor motor 21a can be controlled by an inverter.

[0025] The four-way switching valve 22 switches between a cooling operation connection state and a heating operation connection state by switching the connection state of the main refrigerant circuit 10. In the cooling operation connection state (dotted line state in FIG. 1), the discharge side of the compressor 21 is connected to the gas side of the heat source side heat exchanger 23, and the suction side of the compressor 21 is connected to the gas side stop valve 29. In the heating operation connection state (solid line state in FIG. 1), the discharge side of the compressor 21 is connected to the gas side stop valve 29, and the suction side of the compressor 21 is connected to the gas side of the heat source side heat exchanger 23. One of the connection ports of the four-way switching valve 22 is connected to the discharge side of the compressor 21 via a first pipe 51.

[0026] The heat source side heat exchanger 23 functions as a radiator (condenser) of high pressure refrigerant in the refrigeration cycle during cooling operation, and functions as a heat absorber (evaporator) of low pressure refrigerant in the refrigeration cycle during heating operation.

[0027] The heat source-side fan 24 supplies air outside the space to be air-conditioned (such as outside air) to the heat source-side heat exchanger 23 within the heat source unit 2, exchanges heat with the refrigerant in the heat source-side heat exchanger 23, and then generates an air flow for discharging the air to the outside of the heat source unit 2. The heat source-side fan 24 is rotationally driven by a heat source-side fan motor 24a.

[0028] The heat source side expansion valve 25 is a throttling mechanism having a function of reducing the pressure of the refrigerant. The heat source side expansion valve 25 is provided between the liquid side of the heat source side heat exchanger 23 and the liquid side stop valve 28. The heat source side expansion valve 25 is an electric expansion valve whose opening degree can be adjusted by control of the control unit 70.

[0029] The accumulator 26 is provided between the suction side of the compressor 21 and one of the connection ports of the four-way switching valve 22. In the main refrigerant circuit 10 in the heating operation connection state, the accumulator 26 is provided between the compressor 21 and the heat source side heat exchanger 23. Inside the accumulator 26, an end of the second pipe 52 connected to the suction side of the compressor 21 and an end of the third pipe 53 connected to one of the connection ports of the four-way switching valve 22 are arranged. The second pipe 52 and the third pipe 53 are connected to each other via the accumulator 26.

[0030] The accumulator 26 is a refrigerant container capable of temporarily storing excess refrigerant in the main refrigerant circuit 10 as liquid refrigerant. The refrigerant circulating in the main refrigerant circuit 10 flows through the third piping 53 and into the accumulator 26. The refrigerant stored in the accumulator 26 flows through the second piping 52 and out of the accumulator 26.

[0031] The liquid-side shutoff valve 28 is a manual valve that is disposed at the connection portion of the heat source unit 2 with the liquid-side refrigerant connection pipe 6.

[0032] The gas-side shutoff valve 29 is a manual valve arranged at the connection portion of the heat source unit 2 with the gas-side refrigerant connection pipe 7 .

[0033] The heat source unit 2 has a heat source unit control unit 20 that controls the operation of each component that constitutes the heat source unit 2. The heat source unit control unit 20 constitutes a control unit 70. The heat source unit control unit 20 is, for example, a microcomputer including a CPU, a memory, etc. The heat source unit control unit 20 is connected to the utilization unit control unit 30 of the utilization unit 3 via a communication line, and transmits and receives control signals, etc.

[0034] (1-2) Unit 3 The utilization unit 3 is installed on the walls and ceiling of a room or the like which is a space to be air-conditioned. As shown in FIG.

[0035] The use-side heat exchanger 31 functions as a heat absorber (evaporator) of low-pressure refrigerant in the refrigeration cycle during cooling operation, and functions as a heat radiator (condenser) of high-pressure refrigerant in the refrigeration cycle during heating operation. A pipe extending from the liquid side of the use-side heat exchanger 31 is connected to the liquid-side refrigerant connection pipe 6. A pipe extending from the gas side of the use-side heat exchanger 31 is connected to the gas-side refrigerant connection pipe 7. As a result, the compressor 21, the heat-source-side heat exchanger 23, the heat-source-side expansion valve 25, and the use-side heat exchanger 31 are connected in a ring shape to the main refrigerant circuit 10.

[0036] The usage-side fan 32 supplies air from the space to be air-conditioned to the usage-side heat exchanger 31 in the usage unit 3, and generates an air flow for discharging the air to the space to be air-conditioned after heat exchange with the refrigerant in the usage-side heat exchanger 31. The usage-side fan 32 is rotationally driven by a usage-side fan motor 32a.

[0037] The utilization unit 3 has a utilization unit control unit 30 that controls the operation of each component that constitutes the utilization unit 3. The utilization unit control unit 30 constitutes a control unit 70. The utilization unit control unit 30 is, for example, a microcomputer including a CPU, a memory, etc. The utilization unit control unit 30 is connected to the heat source unit control unit 20 of the heat source unit 2 via a communication line, and transmits and receives control signals, etc.

[0038] (1-3) Remote Control 8 The remote control 8 is placed in a space to be air-conditioned or in a specific space in a building having a space to be air-conditioned. The remote control 8 functions as an input device for a user of the refrigeration cycle apparatus 100 to input various instructions to the refrigeration cycle apparatus 100. For example, the user operates the remote control 8 to switch the operation state (heating operation or cooling operation) of the refrigeration cycle apparatus 100 or adjust the set temperature of the space to be air-conditioned. The remote control 8 also functions as a display device for displaying the operation state of the refrigeration cycle apparatus 100 and predetermined notification information. The remote control 8 is connected to the heat source unit control unit 20 and the utilization unit control unit 30 via communication lines, and transmits and receives signals to and from each other.

[0039] (1-4) Control unit 70 In the refrigeration cycle apparatus 100, the heat source unit control section 20 and the utilization unit control section 30 are connected via a communication line to configure a control section 70, which is hardware that controls the operation of the refrigeration cycle apparatus 100. The control by the control section 70 is realized by the heat source unit control section 20 and the utilization unit control section 30 operating integrally.

[0040] 2, the control unit 70 is electrically connected to actuators included in the heat source unit 2. The actuators included in the heat source unit 2 are specifically the compressor motor 21a of the compressor 21, the heat source side expansion valve 25, and the heat source side fan motor 24a of the heat source side fan 24. The control unit 70 is also electrically connected to the remote control 8 and actuators included in the utilization unit 3. The actuator included in the utilization unit 3 is specifically the utilization side fan motor 32a of the utilization side fan 32.

[0041] 2, the control unit 70 mainly includes a storage unit 71, a communication unit 72, a mode control unit 73, an actuator control unit 74, and a display control unit 75. Each of these elements realizes a specific function of the control unit 70. The control unit 70 executes these functions by executing control programs stored in a ROM, a RAM, a flash memory, or the like.

[0042] The storage unit 71 stores predetermined information in a predetermined storage area upon request from other elements of the control unit 70. The predetermined information is, for example, the result of a calculation executed by the control unit 70 and a command input to the remote control 8.

[0043] The communication unit 72 functions as a communication interface for transmitting and receiving signals to and from each device connected to the control unit 70. The communication unit 72 transmits a predetermined signal to a specified actuator upon request from the actuator control unit 74. The communication unit 72 receives a signal output from the remote control 8 or the like, and requests the storage unit 71 to store the signal in a predetermined storage area.

[0044] The mode control unit 73 switches the operation mode of the refrigeration cycle apparatus 100 and the like.

[0045] Based on a control program, the actuator control unit 74 controls the operation of each actuator included in the refrigeration cycle apparatus 100. For example, the actuator control unit 74 controls the rotation speed of the compressor 21, the opening degree of the heat source side expansion valve 25, the rotation speed of the heat source side fan 24, the rotation speed of the utilization side fan 32, etc. in real time according to the set temperature, etc.

[0046] The display control unit 75 is a functional unit that controls the operation of the remote control 8 as a display device. The display control unit 75 causes the remote control 8 to output predetermined information in order to notify a user of information related to the operating state and status of the refrigeration cycle apparatus 100. For example, the display control unit 75 causes the display of the remote control 8 to display information such as the operating mode and the set temperature.

[0047] (2) Operation Mode of the Refrigeration Cycle Apparatus 100 The refrigeration cycle apparatus 100, which is an air-conditioning apparatus, operates in a cooling operation mode or a heating operation mode to adjust the temperature and humidity of the air in the space to be air-conditioned. The control unit 70 determines whether the operation mode should be the cooling operation mode or the heating operation mode, based on an instruction input to the remote control 8 by the user.

[0048] (2-1) Cooling operation mode In the cooling operation mode, the control unit 70 sets the four-way switching valve 22 to a cooling operation connection state to perform cooling operation in the space to be air-conditioned. In the cooling operation mode, the control unit 70 controls the rotation speed of the compressor 21, for example, so that the evaporation temperature of the refrigerant in the main refrigerant circuit 10 becomes a target evaporation temperature.

[0049] In the cooling operation mode, the gas refrigerant discharged from the compressor 21 of the heat source unit 2 passes through the first pipe 51 and the four-way switching valve 22 and flows through the heat source side heat exchanger 23. The refrigerant flowing through the heat source side heat exchanger 23 releases heat or condenses by exchanging heat with outdoor air, and then flows toward the heat source side expansion valve 25. The control unit 70 controls the opening degree of the heat source side expansion valve 25 located between the heat source side heat exchanger 23 and the utilization side heat exchanger 31 so that conditions such as the degree of subcooling of the heat source side heat exchanger 23 and the degree of superheat of the utilization side heat exchanger 31 reaching predetermined target values ​​are satisfied.

[0050] The refrigerant decompressed by the heat source side expansion valve 25 passes through the liquid side shutoff valve 28 and the liquid side refrigerant communication pipe 6, flows into the utilization unit 3, and flows through the utilization side heat exchanger 31. The refrigerant flowing through the utilization side heat exchanger 31 absorbs heat or evaporates by exchanging heat with the air in the space to be air-conditioned, and then flows through the gas side refrigerant communication pipe 7 and flows into the heat source unit 2 from the gas side shutoff valve 29. The refrigerant that has flowed into the heat source unit 2 passes through the four-way switching valve 22, the third pipe 53, the accumulator 26, and the second pipe 52, and is sucked into the compressor 21 again. In the accumulator 26, the liquid refrigerant that has not been completely evaporated in the utilization side heat exchanger 31 is stored as surplus refrigerant.

[0051] (2-2) Heating operation mode In the heating operation mode, the control unit 70 sets the four-way switching valve 22 to a heating operation connection state and performs heating operation in the space to be air-conditioned. In the heating operation mode, the control unit 70 controls the rotation speed of the compressor 21, for example, so that the condensation temperature of the refrigerant in the main refrigerant circuit 10 becomes a target condensation temperature.

[0052] In the heating operation mode, the gas refrigerant discharged from the compressor 21 of the heat source unit 2 passes through the first pipe 51, the four-way switching valve 22, the gas side shutoff valve 29, and the gas side refrigerant connection pipe 7, flows into the utilization unit 3, and flows through the utilization side heat exchanger 31. The refrigerant flowing through the utilization side heat exchanger 31 releases heat or condenses by exchanging heat with the air in the space to be air-conditioned, and then flows through the liquid side refrigerant connection pipe 6 and flows into the heat source unit 2 through the liquid side shutoff valve 28. The refrigerant that has flowed into the heat source unit 2 is decompressed by the heat source side expansion valve 25. The control unit 70 controls the opening degree of the heat source side expansion valve 25 located between the utilization side heat exchanger 31 and the heat source side heat exchanger 23 so that conditions such as the degree of subcooling of the utilization side heat exchanger 31 and the degree of superheat of the heat source side heat exchanger 23 reaching predetermined target values ​​are satisfied.

[0053] The refrigerant decompressed by the heat source side expansion valve 25 flows through the heat source side heat exchanger 23. The refrigerant flowing through the heat source side heat exchanger 23 absorbs heat or evaporates by exchanging heat with outdoor air, and then passes through the four-way switching valve 22, the third pipe 53, the accumulator 26, and the second pipe 52, and is sucked back into the compressor 21. In the accumulator 26, liquid refrigerant that has not been completely evaporated in the heat source side heat exchanger 23 is stored as surplus refrigerant.

[0054] (3) Detailed configuration The circulating refrigerant amount and the stagnant refrigerant amount are defined as follows. The circulating refrigerant amount is the weight of the circulating refrigerant, which is the refrigerant circulating through the main refrigerant circuit 10 during operation of the refrigeration cycle device 100. The stagnant refrigerant amount is the weight of the stagnant refrigerant, which is the liquid refrigerant stored in the accumulator 26 during operation of the refrigeration cycle device 100. The stagnant refrigerant does not circulate through the main refrigerant circuit 10 during operation of the refrigeration cycle device 100. The gas refrigerant in the accumulator 26 is a part of the circulating refrigerant and has the same composition as the circulating refrigerant. The temperature of the gas refrigerant in the accumulator 26 is the same as the temperature of the stagnant refrigerant. For example, when the temperature of the stagnant refrigerant is -40°C, refrigerant at -40°C flows into the accumulator 26, and gas refrigerant at -40°C flows out of the accumulator 26. The temperature of the stagnant refrigerant is the same as the temperature of the gas outside the accumulator 26.

[0055] The space in the main refrigerant circuit 10 in which the refrigerant is sealed is regarded as a single container, and this container is called the refrigerant circuit container. Inside the refrigerant circuit container, gaseous circulating refrigerant and liquid retained refrigerant exist in a gas-liquid equilibrium state. If the amount of circulating refrigerant in the refrigerant circuit container is W1 and the amount of retained refrigerant in the refrigerant circuit container is W2, the amount of sealed refrigerant W3, which is the weight of the refrigerant sealed in the main refrigerant circuit 10, is expressed by the following formula (I). W3 = W1 + W2 (I)

[0056] The charged refrigerant amount W3 is a value that can be measured when the refrigerant is charged into the main refrigerant circuit 10. The retained refrigerant amount W2 is, for example, the product of the effective volume of the accumulator 26 and the saturated liquid density of the refrigerant at the pressure of the refrigerant sucked into the compressor 21. The retained refrigerant amount W2 may also be calculated based on the liquid level of the liquid refrigerant stored in the accumulator 26. The liquid level of the liquid refrigerant is measured, for example, using a liquid level gauge attached to the accumulator 26.

[0057] The weight ratio of the gas refrigerant in the refrigerant circuit vessel is called the refrigerant quality. The refrigerant quality Q is expressed by the following formula (II) or formula (III). Q = W1 / (W1 + W2) (II) Q = (W3 - W2) / W3 (III)

[0058] The range of the refrigerant quality Q is equal to or greater than 0 and equal to or less than 1. In the refrigeration cycle apparatus 100, the refrigerant quality exceeds a predetermined value determined according to the type of refrigerant sealed in the main refrigerant circuit 10. Specifically, the operation of the refrigeration cycle apparatus 100 is controlled and the main refrigerant circuit 10 is designed so that the refrigerant quality exceeds the predetermined value.

[0059] For example, the control unit 70 controls a parameter related to the wetness of the mixed refrigerant at the inlet of the accumulator 26 so that the refrigerant quality exceeds a predetermined value. In this case, the control unit 70 adjusts the opening of the heat source side expansion valve 25 and the rotation speed of the heat source side fan 24 so that the refrigerant quality exceeds the predetermined value. Also, the effective volume of the accumulator 26 is designed to be equal to or less than a predetermined value so that the refrigerant quality exceeds the predetermined value.

[0060] According to formula (III), the higher the refrigerant quality, the smaller the amount of stagnant refrigerant. Therefore, for reasons described later, the higher the refrigerant quality, the smaller the deviation between the composition of the circulating refrigerant and the base composition. The base composition is the composition of the non-azeotropic refrigerant mixture when it is charged into the main refrigerant circuit 10. Next, the deviation between the composition of the circulating refrigerant and the base composition will be explained with reference to Figs. 3 and 4. Hereinafter, the mixed refrigerant charged into the main refrigerant circuit 10 is assumed to be R454C. R454C contains 21.5 mass% R32 and 78.5 mass% R1234yf. Therefore, the base composition of the mixed refrigerant charged into the main refrigerant circuit 10 is composed of 21.5 mass% R32 and 78.5 mass% R1234yf.

[0061] Figure 3 shows a Mollier diagram with the saturated liquid line L1 and the dry saturated vapor line L2 of R454C. The solid line L3 is the -40°C isotherm of R454C. The dotted line L4 represents the state of R454C at a given refrigerant quality. The pressure P1 at the intersection of the solid line L3 and the dotted line L4 is the pressure of R454C at -40°C at a given refrigerant quality.

[0062] FIG. 4 is a vapor-liquid equilibrium diagram of a mixed refrigerant of R32 and R1234yf at pressure P1 in FIG. 3. The horizontal axis of FIG. 4 represents the content (0 mass % to 100 mass %) of R32 contained in the mixed refrigerant. The vertical axis of FIG. 4 represents the temperature of the mixed refrigerant. FIG. 4 shows a boiling point curve L5 and a dew point curve L6. The region lower than the boiling point curve L5 is the liquid phase. The region higher than the dew point curve L6 is the gas phase. The region between the boiling point curve L5 and the dew point curve L6 is the gas-liquid mixed phase.

[0063] As shown in Fig. 4, a mixed refrigerant having a base composition with an R32 content of 21.5 mass% is in a gas-liquid two-phase state at a temperature of -40°C. The R32 content S1 at the intersection of the line L7 at a temperature of -40°C and the boiling point curve L5 is the R32 content of the stagnant refrigerant. The R32 content S2 at the intersection of the line L7 at a temperature of -40°C and the dew point curve L6 is the R32 content of the circulating refrigerant. In the refrigeration cycle device 100, the refrigerant quality is limited within a predetermined range so that the difference between the R32 content S2 of the circulating refrigerant and the R32 content (21.5 mass%) of the mixed refrigerant having the base composition is equal to or less than a predetermined value.

[0064] Next, a method for determining the range of the refrigerant quality will be described with reference to Figs. 5 and 6. The horizontal axis of Fig. 5 represents the content (mass%) of R32 contained in the mixed refrigerant of R32 and R1234yf. The vertical axis of Fig. 5 represents the temperature glide of the mixed refrigerant. The temperature glide is the difference between the saturated gas temperature of the refrigerant and the saturated liquid temperature of the refrigerant. Hereinafter, the saturated gas temperature of the refrigerant is assumed to be the condensation temperature of the refrigerant. The horizontal axis of Fig. 6 represents the refrigerant quality of the refrigerant sealed in the main refrigerant circuit 10. The vertical axis of Fig. 6 represents the content (mass%) of R32 contained in the circulating refrigerant. In Fig. 6, the content (21.5 mass%) of R32 in the mixed refrigerant of the base composition is indicated by a straight line L8.

[0065] The boiling point of R1234yf is higher than that of R32. Therefore, the content of R1234yf contained in the stagnant refrigerant tends to be higher than the content of R1234yf contained in the circulating refrigerant. Also, the content of R32 contained in the circulating refrigerant tends to be higher than the content of R32 contained in the stagnant refrigerant. Therefore, the smaller the refrigerant quality, the larger the amount of stagnant refrigerant, and the larger the weight of R1234yf contained in the stagnant refrigerant, so the smaller the weight of R1234yf contained in the circulating refrigerant. Therefore, as shown in FIG. 6, the smaller the refrigerant quality, the larger the content of R32 contained in the circulating refrigerant. As shown in FIG. 5, when the content of R32 contained in the circulating refrigerant becomes larger than the content of R32 (21.5 mass%) in the mixed refrigerant of the base composition, the temperature glide decreases. Therefore, the smaller the decrease in temperature glide, the smaller the deviation between the composition of the circulating refrigerant and the base composition.

[0066] In the refrigeration cycle apparatus 100, the range of the refrigerant quality is set so that the drop in temperature glide is 1 K or less. As shown in FIG. 5, when the content of R32 in the mixed refrigerant is the content of R32 in the mixed refrigerant of the base composition (21.5 mass%), the temperature glide is 7.7 K. When the temperature glide drops by 1 K from 7.7 K to 6.7 K, the content of R32 in the mixed refrigerant is 30.0 mass%. In FIG. 6, when the content of R32 in the circulating refrigerant is 30.0 mass%, the refrigerant quality is 0.65. Therefore, when the refrigerant quality is greater than 0.65, the content of R32 in the circulating refrigerant is 21.5 mass% to 30.0 mass%, and the temperature glide is 6.7 K to 7.7 K.

[0067] As described above, in the refrigeration cycle apparatus 100, when the mixed refrigerant charged in the main refrigerant circuit 10 is R454C, the refrigerant quality is set to be greater than 0.65. This limits the temperature glide drop to 1 K or less, and suppresses the deviation between the circulating refrigerant composition and the base composition. In this way, the range of the refrigerant quality is determined based on the temperature glide drop. Next, the temperature glide drop will be described with reference to FIG. 7.

[0068] FIG. 7 shows a Mollier diagram of a mixed refrigerant of R32 and R1234yf. The mixed refrigerant has a first composition or a second composition. The mixed refrigerant having the first composition contains 21.5 mass% R32 and 78.5 mass% R1234yf. The mixed refrigerant having the second composition contains 60.0 mass% R32 and 40.0 mass% R1234yf. FIG. 7 shows a saturated liquid line L11 and a dry saturated vapor line L12 of the mixed refrigerant having the first composition, and a saturated liquid line L21 and a dry saturated vapor line L22 of the mixed refrigerant having the second composition. FIG. 7 shows isotherms at 40° C., 33° C., and 30° C. of the mixed refrigerant having the first composition, and isotherms at 40° C. and 38° C. of the mixed refrigerant having the second composition.

[0069] The first composition is the composition of R454C, which is a mixed refrigerant filled in the main refrigerant circuit 10. In other words, the first composition is a base composition. The second composition is an example of the composition of the circulating refrigerant when liquid refrigerant is stored in the accumulator 26 during operation of the refrigeration cycle apparatus 100. When the refrigeration cycle apparatus 100 is started, the weight of R1234yf contained in the circulating refrigerant decreases as described above, and therefore the composition of the circulating refrigerant gradually changes from the first composition to the second composition.

[0070] FIG. 7 shows condensation processes C11-C12 of the circulating refrigerant with a first composition and C21-C22 of the circulating refrigerant with a second composition. The condensation temperatures of the circulating refrigerants with the first and second compositions are 40° C. The saturated liquid temperature T1 of the circulating refrigerant with the first composition is 33° C. The degree of subcooling of the circulating refrigerant with the first composition in the condensation process is set to 3° C. Therefore, the target value T2 of the temperature of the circulating refrigerant at the outlet of the condenser is set to 30° C., which is 3° C. lower than the saturated liquid temperature T1. When the temperature of the circulating refrigerant at the outlet of the condenser is controlled to be 30° C., which is the same as the target value T2, the saturated liquid temperature T3 of the circulating refrigerant with the second composition after the composition of the circulating refrigerant changes from the first composition to the second composition is 38° C.

[0071] The temperature glide of the circulating refrigerant with the first composition is 7° C. The temperature glide of the circulating refrigerant with the second composition is 2° C. Therefore, when the composition of the circulating refrigerant changes from the first composition to the second composition, the temperature glide decreases by 5° C. The temperature glide decrease corresponds to the value obtained by subtracting the saturated liquid temperature T1 of the circulating refrigerant with the first composition from the saturated liquid temperature T3 of the circulating refrigerant with the second composition.

[0072] In the case of FIG. 7, the saturated liquid temperature T3 of the circulating refrigerant with the second composition is 38°C, so when the temperature of the circulating refrigerant at the outlet of the condenser is controlled to be 30°C, the degree of subcooling is 8°C. Therefore, when the composition of the circulating refrigerant changes from the first composition to the second composition, the refrigeration cycle device 100 is operated in a state where the degree of subcooling is increased by 5°C, and the performance of the condenser may be deteriorated. Therefore, in order to minimize the increase in the degree of subcooling even when the composition of the circulating refrigerant changes, it is preferable that the decrease in the temperature glide is as small as possible. In this embodiment, the maximum allowable amount of decrease in the temperature glide is set to 1K, taking into account the variation in the measured value of the thermistor for measuring the temperature of the circulating refrigerant.

[0073] (4) Features (4-1) Of the refrigerant circulating through the main refrigerant circuit 10, liquid refrigerant that has not been completely evaporated in the evaporator is stored in the accumulator 26 as excess refrigerant. The refrigerant sealed in the main refrigerant circuit 10 is a non-azeotropic refrigerant mixture, which is a mixture of a low boiling point refrigerant and a high boiling point refrigerant. The boiling point of the high boiling point refrigerant is higher than that of the low boiling point refrigerant. Therefore, the stagnant refrigerant, which is the liquid refrigerant stored in the accumulator 26, has a higher content of high boiling point refrigerant than the circulating refrigerant circulating through the main refrigerant circuit 10. As a result, if the stagnant refrigerant is gradually stored in the accumulator 26, the content of high boiling point refrigerant in the circulating refrigerant decreases, and the composition of the circulating refrigerant may deviate from the base composition.

[0074] In the refrigeration cycle apparatus 100, the amount of liquid refrigerant stored in the accumulator 26 is limited depending on the type and amount of refrigerant charged in the main refrigerant circuit 10. Specifically, the refrigeration cycle apparatus 100 is controlled so that the refrigerant quality, which is set depending on the type of refrigerant, exceeds a predetermined value.

[0075] The higher the refrigerant quality, the smaller the amount of retained refrigerant and the larger the amount of circulating refrigerant. Therefore, the higher the refrigerant quality, the more the composition of the circulating refrigerant is prevented from deviating from the base composition. If the composition of the circulating refrigerant deviates from the base composition, the heat exchange performance and controllability of the refrigeration cycle apparatus 100 may decrease. Therefore, the refrigeration cycle apparatus 100 can prevent the deterioration of the heat exchange performance and controllability.

[0076] (4-2) In the refrigeration cycle apparatus 100, the range of refrigerant quality is set so that the amount of change in temperature glide when the composition of the circulating refrigerant deviates from the base composition is equal to or less than a predetermined value. Specifically, the range of refrigerant quality is set so that the amount of decrease in temperature glide is equal to or less than 1 K. For the reasons described above, the greater the amount of decrease in temperature glide, the greater the risk of deterioration in the performance of the condenser. Therefore, the refrigeration cycle apparatus 100 can suppress the deterioration in performance caused by the change in the composition of the circulating refrigerant.

[0077] (4-3) In the refrigeration cycle apparatus 100, a non-azeotropic refrigerant mixture is sealed in the main refrigerant circuit 10. When a refrigerant such as R1123 contained in the non-azeotropic refrigerant mixture generates radicals, it may change into another compound through a disproportionation reaction. The disproportionation reaction is accompanied by the release of a large amount of heat. Therefore, the reliability of the refrigeration cycle apparatus 100 may be reduced if the refrigerant contained in the circulating refrigerant causes a disproportionation reaction.

[0078] In the refrigeration cycle apparatus 100, the composition of the circulating refrigerant is prevented from deviating from the base composition. Therefore, the increase in the content of refrigerants that are likely to cause disproportionation reactions in the circulating refrigerant is suppressed. Therefore, the refrigeration cycle apparatus 100 can suppress a decrease in reliability caused by the disproportionation reactions of the refrigerant.

[0079] (5) Examples As shown in Fig. 6, in the refrigeration cycle apparatus 100, the composition of the circulating refrigerant changes depending on the refrigerant quality. In order to verify the accuracy of the amount of change in the composition of the circulating refrigerant, an experiment was conducted to compare the actual measured value of the composition of the circulating refrigerant with the predicted value of the composition of the circulating refrigerant, as described below. The actual measured value was obtained by measuring the composition of the circulating refrigerant when the refrigerant quality was a predetermined value. The predicted value was obtained by calculating the change in composition based on the vapor-liquid equilibrium state of the refrigerant stored in the accumulator.

[0080] (5-1) Test Equipment Configuration As shown in Fig. 8, a refrigeration cycle apparatus 200, which is a test machine for measuring the actual values ​​of the composition of the circulating refrigerant, has a configuration similar to that of the refrigeration cycle apparatus 100 shown in Fig. 1. However, in the refrigeration cycle apparatus 200, the accumulator 126 is attached to the gas side refrigerant communication pipe 7 outside the heat source unit 2, not inside the heat source unit 2. Inside the heat source unit 2, the second pipe 52 connected to the suction side of the compressor 21 is directly connected to one of the connection ports of the four-way switching valve 22. The accumulator 126 is attached with a liquid level gauge for measuring the volume of the liquid refrigerant stored in the accumulator 126.

[0081] The gas side refrigerant connection pipe 7 is divided into a first connection pipe 7a and a second connection pipe 7b by the accumulator 126. The first connection pipe 7a connects the gas side of the utilization side heat exchanger 31 and the accumulator 126. The second connection pipe 7b connects the accumulator 126 and the gas side shutoff valve 29. A first sampling valve 61 and a second sampling valve 62 are attached to the second connection pipe 7b. The first sampling valve 61 is attached near the accumulator 126. The second sampling valve 62 is attached near the gas side shutoff valve 29.

[0082] (5-2) Test machine operating conditions The refrigeration cycle apparatus 200, which is a test machine, is an air conditioner with a cooling capacity of 4.0 kW. The refrigeration cycle apparatus 200 is operated in a cooling operation mode. The length of the liquid side refrigerant connection pipe 6 is 5.0 m. The outer diameter of the liquid side refrigerant connection pipe 6 is 6.4 mm. The length of the gas side refrigerant connection pipe 7 is 5.0 m. The outer diameter of the gas side refrigerant connection pipe 7 is 9.5 mm.

[0083] The non-azeotropic refrigerant mixture filled in the main refrigerant circuit 10 of the refrigeration cycle apparatus 200 is R454C. R454C contains 21.5% by mass of R32 and 78.5% by mass of R1234yf.

[0084] The main refrigerant circuit 10 is initially charged with a specified amount of refrigerant, and then a predetermined amount of refrigerant is additionally charged so that liquid refrigerant accumulates in the accumulator 126. When the additional refrigerant is charged, a parameter related to the wetness of the circulating refrigerant is manually controlled so that liquid refrigerant is accumulated in the accumulator 126.

[0085] (5-3) Measurement results The gas refrigerant in the accumulator 126 and the circulating refrigerant were sampled, and the compositions of the refrigerants were measured by gas chromatography to obtain actual values ​​of the composition of the circulating refrigerant. The gas refrigerant in the accumulator 126 was sampled from the first sampling valve 61. The circulating refrigerant was sampled from the second sampling valve 62.

[0086] As shown in the table below, for each of Examples 1 to 3, the actual measured value of the composition of the gas refrigerant in the accumulator 126, the actual measured value of the composition of the circulating refrigerant, and the predicted value of the composition of the circulating refrigerant were acquired or calculated. [Table 1]

[0087] In the above table, the refrigerant circulation amount is the weight of refrigerant circulating through the main refrigerant circuit 10 per hour. The refrigerant charge amount is the weight of refrigerant charged in the main refrigerant circuit 10 after additional refrigerant has been charged. The liquid storage amount is the weight of liquid refrigerant stored in the accumulator 126. The refrigerant quality is calculated from the following formula (IV) based on the above formula (III). Refrigerant quality = (refrigerant charge amount - liquid storage amount) / refrigerant charge amount (IV)

[0088] The refrigerant qualities are different from one another in Examples 1 to 3. In the above table, the measured and predicted values ​​of the composition are listed in the order of the content (mass%) of R32 and the content (mass%) of R1234yf.

[0089] Experimental results confirmed that the measured composition of the circulating refrigerant was very close to the predicted composition of the circulating refrigerant, and that the measured composition of the gas refrigerant in the accumulator 126 was nearly the same as the measured composition of the circulating refrigerant.

[0090] Furthermore, it was confirmed that the higher the refrigerant quality, the smaller the difference between the measured R32 content in the circulating refrigerant composition and the R32 content in the base composition (21.5 mass%). Therefore, it was confirmed that the higher the refrigerant quality, the more suppressed the deviation of the circulating refrigerant composition from the base composition.

[0091] (6) Variations In the embodiment, the mixed refrigerant filled in the main refrigerant circuit 10 is R454C. R454C contains 21.5 mass% R32 and 78.5 mass% R1234yf. In this case, the content of R32 is limited to 30.0 mass% or less so that the temperature glide drop when the composition of the circulating refrigerant deviates from the base composition is 1 K or less. As a result, the refrigerant quality is set to be higher than 0.65.

[0092] Next, we will explain how to set the refrigerant quality when the first to third mixed refrigerants other than R454C are charged into the main refrigerant circuit 10. The method for determining the range of refrigerant quality when the first to third mixed refrigerants are used is the same as the method for determining the range of refrigerant quality when R454C is used, as shown in Figures 5 and 6.

[0093] (6-1) First mixed refrigerant The first mixed refrigerant contains R1132(E) and R1234yf. The base composition of the first mixed refrigerant is 23.0 mass% R1132(E) and 77.0 mass% R1234yf. When the content of R1132(E) in the first mixed refrigerant is the content of R1132(E) in the first mixed refrigerant in the base composition (23.0 mass%), the temperature glide is 7.0 K. When the temperature glide decreases by 1 K from 7.0 K to 6.0 K, the content of R1132(E) in the first mixed refrigerant is 45.0 mass%.

[0094] In this case, the content of R1132(E) is limited to 45.0 mass% or less so that the drop in temperature glide when the composition of the circulating refrigerant deviates from the base composition is 1 K or less. Therefore, when the first mixed refrigerant is used, the refrigerant quality is set to be higher than 0.15.

[0095] (6-2) Second mixed refrigerant The second mixed refrigerant contains R1132(E), R1234yf, and R32. The base composition of the second mixed refrigerant is 22.0 mass% R1132(E), 56.0 mass% R1234yf, and 22.0 mass% R32. When the content of R1132(E) in the second mixed refrigerant is the content of R1132(E) in the second mixed refrigerant of the base composition (22.0 mass%), the temperature glide is 5.3K. When the temperature glide decreases by 1K from 5.3K to 4.3K, the content of R1132(E) in the second mixed refrigerant is 32.0 mass%.

[0096] In this case, the content of R1132(E) is limited to 32.0 mass% or less so that the temperature glide drop when the composition of the circulating refrigerant deviates from the base composition is 1 K or less. Therefore, when the second mixed refrigerant is used, the refrigerant quality is set to be higher than 0.22.

[0097] (6-3) The third mixed refrigerant The third mixed refrigerant contains R1123 and R1234yf. The base composition of the third mixed refrigerant is 34.0 mass% R1123 and 66.0 mass% R1234yf. When the content of R1123 in the third mixed refrigerant is the content of R1123 in the third mixed refrigerant of the base composition (34.0 mass%), the temperature glide is 8.0 K. When the temperature glide decreases by 1 K from 8.0 K to 7.0 K, the content of R1123 in the third mixed refrigerant is 61.0 mass%.

[0098] In this case, the content of R1123 is limited to 61.0 mass% or less so that the drop in temperature glide when the composition of the circulating refrigerant deviates from the base composition is 1 K or less. Therefore, when the third mixed refrigerant is used, the refrigerant quality is set to be higher than 0.12.

[0099] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims. [Explanation of symbols]

[0100] 10: Main refrigerant circuit (refrigerant circuit) 21: Compressor 23: Heat source side heat exchanger (evaporator, condenser) 25: Heat source side expansion valve (expansion mechanism) 26: Accumulator 31: User side heat exchanger (condenser, evaporator) 70: Control section 100: Refrigeration cycle device [Prior art documents] [Patent documents]

[0101] [Patent Document 1] JP 2015-200431 A

Claims

1. A compressor (21); a condenser (23); an expansion mechanism (25); an evaporator (31); an accumulator (26); a refrigerant circuit (10) in which the compressor, the condenser, the expansion mechanism, the evaporator, and the accumulator are connected in a ring shape and in which a mixed refrigerant is sealed; Equipped with when the amount of the mixed refrigerant charged in the refrigerant circuit is a first amount and the amount of the liquid refrigerant stored in the accumulator is a second amount, the first value obtained by subtracting the second amount from the first amount and dividing the result by the first amount exceeds a value determined based on an amount of change in temperature glide of the mixed refrigerant, The mixed refrigerant is a non-azeotropic mixed refrigerant. A refrigeration cycle device (100).

2. The first value is a value such that the amount of change is 1K or less. The refrigeration cycle device according to claim 1.

3. the second amount is a product of an effective volume of the accumulator and a saturated liquid density of the mixed refrigerant at a pressure of the mixed refrigerant drawn into the compressor. The refrigeration cycle device according to claim 1 or 2.

4. The accumulator further includes a control unit (70) for controlling a parameter related to the wetness of the mixed refrigerant at the inlet of the accumulator. The refrigeration cycle device according to claim 1 or 2.

5. The control unit controls the parameter by adjusting at least the opening of the heat source side expansion valve (25) so that the first value exceeds a value determined based on the amount of change. The refrigeration cycle device according to claim 4.

6. The accumulator has an effective volume equal to or less than a predetermined value. The refrigeration cycle device according to claim 1 or 2.

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