Refrigeration cycle device

Abstract

A refrigeration cycle device (100) is provided with a compressor (21), a use-side heat exchanger (31), a heat-source-side expansion valve (25), a heat-source-side heat exchanger (23), a tank (26), and a main refrigerant circuit (10). A non-azeotropic refrigerant mixture is sealed in the main refrigerant circuit (10). A first value obtained by dividing a value obtained by subtracting the second amount from the first amount by the first amount exceeds a value determined from the mixed refrigerant. The first amount is the amount of the mixed refrigerant enclosed in the main refrigerant circuit (10). The second amount is the amount of liquid refrigerant stored in the tank (26).

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device. Background Art

[0002] In the past, a refrigeration cycle device using a non-azeotropic mixed refrigerant is known. Patent document 1 (Japanese Patent Publication No. 2015-200431) discloses an air conditioning device including a storage tank connected to the suction side of a compressor and using a non-azeotropic mixed refrigerant obtained by mixing a low-boiling-point refrigerant with a high-boiling-point refrigerant. Summary of the invention Technical problem to be solved by the invention

[0003] In such a refrigeration cycle device, there is a tendency that the remaining refrigerant accumulated in the storage tank is a liquid refrigerant containing a large amount of high-boiling-point refrigerant, and the circulating refrigerant circulating in the refrigerant circuit of the refrigeration cycle device is a refrigerant containing a large amount of low-boiling-point refrigerant. Therefore, the composition of the circulating refrigerant deviates from the basic composition of the non-azeotropic mixed refrigerant, and the heat exchange performance and controllability of the refrigeration cycle device may be reduced. Technical solutions adopted to solve technical problems

[0004] The refrigeration cycle device of the first viewpoint includes a compressor, a condenser, an expansion mechanism, an evaporator, a storage tank and a refrigerant circuit. In the refrigerant circuit, the compressor, the condenser, the expansion mechanism, the evaporator and the storage tank are connected in a ring shape. A mixed refrigerant is sealed in the refrigerant circuit. The mixed refrigerant is a non-azeotropic mixed refrigerant. The first value obtained by subtracting the second amount from the first amount and dividing it by the first amount exceeds the 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 storage tank.

[0005] In the refrigeration cycle device of the first aspect, the amount of liquid refrigerant stored in the storage tank is limited according to the type and amount of refrigerant sealed in the refrigerant circuit. This prevents the composition of the refrigerant circulating in the refrigerant circuit from deviating from the basic composition of the non-azeotropic mixed refrigerant sealed in the refrigerant circuit.

[0006] The refrigeration cycle device of the second aspect is the refrigeration cycle device of the first aspect, wherein the second quantity is the product of the effective volume of the storage tank and the saturated liquid density of the mixed refrigerant at the pressure of the mixed refrigerant sucked into the compressor.

[0007] The refrigeration cycle device of the third viewpoint is based on the refrigeration cycle device of the first viewpoint or the second viewpoint, and the mixed refrigerant sealed in the refrigerant circuit has a first composition. When the liquid refrigerant is stored in the storage tank, the mixed refrigerant circulating in the refrigerant circuit has a second composition. The first value is set so that the second value obtained by subtracting T1 from T3 is less than 1K. T1 is the saturated liquid temperature of the mixed refrigerant having the first composition. T2 is the target value of the temperature of the mixed refrigerant having the first composition at the outlet of the condenser. T3 is the 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 storage tank is set so that the change amount of temperature glide when the composition of the refrigerant circulating in the refrigerant circuit deviates from the basic composition is less than a specified value. The temperature glide is the difference between the saturated gas temperature of the refrigerant and the saturated liquid temperature of the refrigerant. Thus, the composition of the refrigerant circulating in the refrigerant circuit is suppressed from deviating from the basic composition.

[0009] The 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 includes 21.5 mass % of R32 and 78.5 mass % of R1234yf. The first value exceeds 0.65.

[0010] The 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 includes 23.0 mass % of R1132(E) and 77.0 mass % of R1234yf. The first value exceeds 0.15.

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

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

[0013] A refrigeration cycle device according to an eighth aspect is the refrigeration cycle device according to any one of the first to seventh aspects, further comprising a control unit that controls a parameter related to the humidity of the mixed refrigerant at the inlet of the storage tank.

[0014] In the refrigeration cycle apparatus according to the eighth aspect, for example, by controlling the opening degree of the expansion mechanism, the composition of the refrigerant circulating in the refrigerant circuit is suppressed from deviating from the basic 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 storage tank has an effective volume that is less than a predetermined value.

[0016] In the refrigeration cycle apparatus according to the ninth aspect, by setting the upper limit value of the effective volume of the accumulator, the composition of the refrigerant circulating in the refrigerant circuit is suppressed from deviating from the basic composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram showing an example of the overall structure of the refrigeration cycle apparatus 100 . Figure 2 It is a block diagram of the control unit 70. Figure 3 This is the Mollier line diagram of R454C. Figure 4 This is the gas-liquid equilibrium diagram of the mixed refrigerant of R32 and R1234yf. Figure 5 This is a graph showing the relationship between the content of R32 and the temperature glide for a mixed refrigerant of R32 and R1234yf. Figure 6 This is a diagram showing the relationship between the refrigerant quality when R454C is used and the content rate of R32 in the circulating refrigerant. Figure 7 It is a diagram for explaining the reduction amount of temperature glide. Figure 8 This is a diagram showing an example of the overall configuration of a refrigeration cycle apparatus 200 as a testing machine for measuring the composition of a circulating refrigerant. DETAILED DESCRIPTION

[0018] (1) Structure of Refrigeration Cycle Apparatus 100 The refrigeration cycle apparatus 100 is an air-conditioning apparatus that performs cooling operation and heating operation of a predetermined air-conditioning target space using a vapor compression refrigeration cycle.

[0019] like Figure 1 As shown, the refrigeration cycle device 100 mainly includes a heat source unit 2, a utilization unit 3, a liquid-side refrigerant communication pipe 6, a gas-side refrigerant communication pipe 7, a remote controller 8, and a control unit 70. In the refrigeration cycle device 100, the heat source unit 2 and the utilization unit 3 are connected via the liquid-side refrigerant communication pipe 6 and the gas-side refrigerant communication pipe 7 to form a main refrigerant circuit 10 for refrigerant circulation.

[0020] In the refrigeration cycle apparatus 100 , the refrigerant sealed in the main refrigerant circuit 10 performs a vapor compression refrigeration cycle in which the refrigerant 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, the 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 mixed refrigerant. The non-azeotropic mixed refrigerant is a mixture of a plurality 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 an air-conditioned space. Figure 1 As shown, the heat source unit 2 mainly includes a compressor 21, a four-way reversing valve 22, a heat source side heat exchanger 23, a heat source side fan 24, a heat source side expansion valve 25, a storage tank 26, a liquid side stop valve 28, and a gas side stop valve 29.

[0024] The compressor 21 is a device that compresses the low-pressure refrigerant in the refrigeration cycle to a high pressure. The compressor 21 has a closed structure that drives a rotary, scroll, or other variable-volume compression element (not shown) to rotate through a compressor motor 21a. The compressor motor 21a can control the operating frequency (rotation speed of the compressor 21) by an inverter.

[0025] The four-way reversing valve 22 switches the cooling operation connection state and the heating operation connection state by switching the connection state of the main refrigerant circuit 10. Figure 1 In the dotted line state), 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 ( Figure 1 In the solid line state), 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 reversing valve 22 is connected to the discharge side of the compressor 21 via the first pipe 51.

[0026] The heat source side heat exchanger 23 functions as a heat sink (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 generates an air flow for supplying air (external air, etc.) outside the air-conditioning target space to the heat source side heat exchanger 23 in the heat source unit 2, and exchanging heat with the refrigerant in the heat source side heat exchanger 23 before being discharged to the outside of the heat source unit 2. The heat source side fan 24 is driven to rotate by a heat source side fan motor 24a.

[0028] The heat source side expansion valve 25 is a throttling mechanism having a function of decompressing 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 the 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 reversing 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. An end of a second pipe 52 connected to the suction side of the compressor 21 and an end of a third pipe 53 connected to one of the connection ports of the four-way reversing valve 22 are arranged inside the accumulator 26. 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 that can temporarily store the excess refrigerant in the main refrigerant circuit 10 as liquid refrigerant. The refrigerant circulating in the main refrigerant circuit 10 flows through the third pipe 53 and flows into the inside of the accumulator 26. The refrigerant stored in the accumulator 26 flows through the second pipe 52 and flows out of the accumulator 26.

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

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

[0033] The heat source unit 2 has a heat source unit control unit 20 that controls the operation of each component constituting the heat source unit 2. The heat source unit control unit 20 constitutes the control unit 70. The heat source unit control unit 20 is, for example, a microcomputer including a CPU and 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 / receives control signals, etc.

[0034] (1-2) Utilization Unit 3 The utilization unit 3 is installed on the wall and ceiling of a room or the like that is the air-conditioned space. Figure 1 As shown, the utilization unit 3 mainly includes a utilization-side heat exchanger 31 and a utilization-side fan 32 .

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

[0036] The usage side fan 32 generates an air flow for supplying air of the air-conditioned space to the usage side heat exchanger 31 in the usage unit 3 and discharging the air to the air-conditioned space after exchanging heat with the refrigerant in the usage side heat exchanger 31. The usage side fan 32 is driven to rotate 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 constituting the utilization unit 3. The utilization unit control unit 30 constitutes the control unit 70. The utilization unit control unit 30 is, for example, a microcomputer including a CPU and 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 / receives control signals, etc.

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

[0039] (1-4) Control Unit 70 In the refrigeration cycle device 100, the heat source unit control unit 20 and the utilization unit control unit 30 are connected via a communication line to form a control unit 70 that is hardware for controlling the operation of the refrigeration cycle device 100. The control of the control unit 70 is achieved by the heat source unit control unit 20 and the utilization unit control unit 30 operating in unison.

[0040] like Figure 2As shown, the control unit 70 is electrically connected to the actuator included in the heat source unit 2. Specifically, the actuator included in the heat source unit 2 is 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 controller 8 and the actuator included in the utilization unit 3. Specifically, the actuator included in the utilization unit 3 is the utilization side fan motor 32a of the utilization side fan 32.

[0041] like Figure 2 As shown, 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 the above elements realizes a specific function of the control unit 70. The control unit 70 executes these functions by executing a control program stored in a ROM, a RAM, a flash memory, etc.

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

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

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

[0045] The actuator control unit 74 controls the operation of each actuator included in the refrigeration cycle device 100 based on a control program. 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, and the rotation speed of the utilization side fan 32 in real time according to a set temperature, etc.

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

[0047] (2) Operation mode of refrigeration cycle device 100 The refrigeration cycle device 100 as an air conditioner operates in a cooling operation mode or a heating operation mode to adjust the temperature and humidity of the air in the air-conditioned space. The control unit 70 determines which operation mode, the cooling operation mode or the heating operation mode, should be operated based on the instruction input by the user to the remote controller 8.

[0048] (2-1) Cooling operation mode In the cooling operation mode, the control unit 70 sets the four-way reversing valve 22 to the cooling operation connection state, thereby performing cooling operation of the air-conditioned space. 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 the 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 reversing valve 22 and flows to the heat source side heat exchanger 23. The refrigerant flowing in the heat source side heat exchanger 23 dissipates heat or condenses by heat exchange with the outdoor air, and then flows toward the heat source side expansion valve 25. The control unit 70 controls the opening 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 as to meet the conditions such as the subcooling degree of the heat source side heat exchanger 23 and the superheating degree of the utilization side heat exchanger 31 becoming the specified target values.

[0050] The refrigerant decompressed in the heat source side expansion valve 25 flows into the utilization unit 3 through the liquid side stop valve 28 and the liquid side refrigerant communication pipe 6, and flows into the utilization side heat exchanger 31. The refrigerant flowing in the utilization side heat exchanger 31 absorbs heat or evaporates by heat exchange with the air in the air-conditioned space, flows through the gas side refrigerant communication pipe 7, and flows into the heat source unit 2 from the gas side stop valve 29. The refrigerant flowing into the heat source unit 2 passes through the four-way reversing 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 completely evaporated in the utilization side heat exchanger 31 is stored as excess refrigerant.

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

[0052] In the heating operation mode, the gas refrigerant discharged from the compressor 21 of the heat source unit 2 flows into the utilization unit 3 through the first pipe 51, the four-way reversing valve 22, the gas-side stop valve 29, and the gas-side refrigerant communication pipe 7, and flows into the utilization unit 3, and flows into the utilization side heat exchanger 31. The refrigerant flowing into the utilization side heat exchanger 31, after heat exchange with the air of the air-conditioned space to dissipate heat or condense, flows through the liquid-side refrigerant communication pipe 6, and flows into the heat source unit 2 from the liquid-side stop valve 28. The refrigerant flowing into the heat source unit 2 is decompressed in the heat source side expansion valve 25. The control unit 70 controls the opening 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 as to satisfy 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 becoming predetermined target values.

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

[0054] (3) Detailed structure The amount of circulating refrigerant and the amount of retained refrigerant are defined as follows. The amount of circulating refrigerant refers to the weight of the circulating refrigerant, wherein the circulating refrigerant is the refrigerant that circulates in the main refrigerant circuit 10 during the operation of the refrigeration cycle device 100. The amount of retained refrigerant refers to the weight of the retained refrigerant, wherein the retained refrigerant is the liquid refrigerant stored in the storage tank 26 during the operation of the refrigeration cycle device 100. The retained refrigerant does not circulate in the main refrigerant circuit 10 during the operation of the refrigeration cycle device 100. The gas refrigerant in the storage tank 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 storage tank 26 is the same as the temperature of the retained refrigerant. For example, when the temperature of the retained refrigerant is -40°C, the refrigerant at -40°C flows into the storage tank 26, and the gas refrigerant at -40°C flows out of the storage tank 26. The temperature of the retained refrigerant is the same as the temperature of the gas outside the storage tank 26.

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

[0056] The sealed refrigerant amount W3 is a value that can be measured when the refrigerant is filled into the main refrigerant circuit 10. The remaining refrigerant amount W2 is, for example, the product of the effective volume of the storage tank 26 and the saturated liquid density of the refrigerant under the pressure of the refrigerant sucked by the compressor 21. In addition, the remaining refrigerant amount W2 can also be calculated based on the height of the liquid level of the liquid refrigerant stored in the storage tank 26. The height of the liquid level of the liquid refrigerant is measured using, for example, a liquid level gauge installed in the storage tank 26.

[0057] The weight ratio of the gas refrigerant in the refrigerant circuit container is referred to as refrigerant quality. The refrigerant quality Q is represented 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 greater than or equal to 0 and less than or equal to 1. In the refrigeration cycle device 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 device 100 is controlled or the main refrigerant circuit 10 is designed so that the refrigerant quality exceeds the predetermined value.

[0059] For example, the control unit 70 controls the parameters related to the humidity of the mixed refrigerant at the inlet of the storage tank 26 so that the refrigerant quality exceeds the prescribed 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 prescribed value. In addition, in order to make the refrigerant quality exceed the prescribed value, the effective volume of the storage tank 26 is designed to be less than the prescribed value.

[0060] According to formula (III), the higher the refrigerant quality, the smaller the amount of retained refrigerant. Therefore, for the reasons described below, the higher the refrigerant quality, the smaller the deviation between the composition of the circulating refrigerant and the basic composition. The basic composition refers to the composition of the non-azeotropic mixed refrigerant when it is sealed in the main refrigerant circuit 10. Next, use Figure 3 and Figure 4 , the deviation of the composition of the circulating refrigerant from the basic composition is explained. In the following, it is assumed that the mixed refrigerant sealed in the main refrigerant circuit 10 is R454C. R454C includes 21.5 mass % of R32 and 78.5 mass % of R1234yf. Therefore, the basic composition of the mixed refrigerant sealed in the main refrigerant circuit 10 is composed of 21.5 mass % of R32 and 78.5 mass % of R1234yf.

[0061] Figure 3It is a Mollier diagram that depicts the saturated liquid line L1 and the dry saturated vapor line L2 of R454C. The solid line L3 is the isotherm of R454C at -40°C. The dotted line L4 represents the state of R454C at a specified 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 specified refrigerant quality.

[0062] Figure 4 yes Figure 3 Gas-liquid equilibrium diagram of a mixed refrigerant of R32 and R1234yf at pressure P1. Figure 4 The horizontal axis represents the content rate (0 mass % to 100 mass %) of R32 included in the mixed refrigerant. Figure 4 The vertical axis represents the temperature of the mixed refrigerant. Figure 4 The boiling point curve L5 and the dew point curve L6 are shown. The area with a temperature lower than the boiling point curve L5 is the liquid phase. The area with a temperature higher than the dew point curve L6 is the gas phase. The area between the boiling point curve L5 and the dew point curve L6 is the gas-liquid mixed phase.

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

[0064] Next, use Figure 5 and Figure 6 , a method for determining the range of refrigerant quality is described. Figure 5 The horizontal axis represents the content (mass %) of R32 included in the mixed refrigerant of R32 and R1234yf. Figure 5 The vertical axis of 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. In the following, it is assumed that the saturated gas temperature of the refrigerant is the condensation temperature of the refrigerant. Figure 6 The horizontal axis represents the refrigerant quality of the refrigerant sealed in the main refrigerant circuit 10 . Figure 6 The vertical axis represents the content (mass %) of R32 included in the circulating refrigerant. Figure 6 In FIG. 1 , the content rate (21.5 mass %) of R32 in the mixed refrigerant of the basic composition is shown by the straight line L8.

[0065] The boiling point of R1234yf is higher than that of R32. Therefore, the content of R1234yf included in the retained refrigerant is often higher than the content of R1234yf included in the circulating refrigerant. In addition, the content of R32 included in the circulating refrigerant is often higher than the content of R32 included in the retained refrigerant. Therefore, the lower the refrigerant quality, the greater the amount of retained refrigerant, the greater the weight of R1234yf included in the retained refrigerant, and therefore, the smaller the weight of R1234yf included in the circulating refrigerant. Therefore, if Figure 6 As shown in FIG. 1 , the lower the refrigerant quality, the greater the content of R32 included in the circulating refrigerant. Figure 5 As shown in FIG. 1 , when the content of R32 included in the circulating refrigerant increases from the content of R32 in the mixed refrigerant of the basic composition (21.5 mass %), the temperature glide decreases. Therefore, the smaller the reduction in temperature glide, the smaller the deviation of the composition of the circulating refrigerant from the basic composition.

[0066] In the refrigeration cycle device 100, the range of the refrigerant quality is set so that the reduction amount of the temperature glide is 1K or less. Figure 5 As shown in FIG. 1 , the temperature glide when the content of R32 in the mixed refrigerant is 21.5 mass % is 7.7 K. The content of R32 in the mixed refrigerant when the temperature glide decreases by 1 K from 7.7 K to 6.7 K is 30.0 mass %. Figure 6 In the case where 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 6.7K to 7.7K.

[0067] As described above, in the refrigeration cycle device 100, when the mixed refrigerant sealed in the main refrigerant circuit 10 is R454C, the refrigerant quality is set to be greater than 0.65. As a result, the reduction in temperature glide is limited to less than 1K, which suppresses the deviation of the composition of the circulating refrigerant from the basic composition. In this way, the range of refrigerant quality is determined based on the reduction in temperature glide. Next, use Figure 7 The amount of reduction in temperature glide will be described.

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

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

[0070] Figure 7 The condensation process C11~C12 of the circulating refrigerant of the first composition and the condensation process C21~C22 of the circulating refrigerant of the second composition are shown in the figure. The condensation temperature of the circulating refrigerant of the first composition and the second composition is 40°C. The saturated liquid temperature T1 of the circulating refrigerant of the first composition is 33°C. The degree of subcooling in the condensation process of the circulating refrigerant of the first composition 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 30°C, which is the same as the target value T2, the saturated liquid temperature T3 of the circulating refrigerant of 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 of the first composition is 7° C. The temperature glide of the circulating refrigerant of the second composition is 2° C. Therefore, when the composition of the circulating refrigerant is changed from the first composition to the second composition, the decrease in the temperature glide is 5° C. In addition, the decrease in the temperature glide is equivalent to the value obtained by subtracting the saturated liquid temperature T1 of the circulating refrigerant of the first composition from the saturated liquid temperature T3 of the circulating refrigerant of the second composition.

[0072] exist Figure 7In the case of , the saturated liquid temperature T3 of the circulating refrigerant of the second composition is 38°C. Therefore, when the temperature of the circulating refrigerant at the outlet of the condenser is controlled to 30°C, the supercooling is 8°C. Therefore, when the composition of the circulating refrigerant changes from the first composition to the second composition, the performance of the condenser may decrease if the refrigeration cycle device 100 is operated in a state where the supercooling increases by 5°C. Therefore, even if the composition of the circulating refrigerant changes, in order to minimize the increase in supercooling, the reduction in temperature glide is as small as possible. In the present embodiment, the maximum allowable reduction in temperature glide is set to 1K in consideration of the deviation in the measured value of the thermistor used to measure the temperature of the circulating refrigerant.

[0073] (4) Features (4-1) The liquid refrigerant that is not completely evaporated in the evaporator among the refrigerant circulating in the main refrigerant circuit 10 is stored in the storage tank 26 as residual refrigerant. The refrigerant sealed in the main refrigerant circuit 10 is a non-azeotropic mixed refrigerant that 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, compared with the circulating refrigerant circulating in the main refrigerant circuit 10, the content of the high-boiling-point refrigerant in the retained refrigerant that is the liquid refrigerant stored in the storage tank 26 is higher. As a result, when the retained refrigerant is gradually stored in the storage tank 26, the content of the high-boiling-point refrigerant in the circulating refrigerant decreases, and the composition of the circulating refrigerant may deviate from the basic composition.

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

[0075] The higher the refrigerant quality, the less the amount of retained refrigerant and the more the circulating refrigerant. Therefore, the higher the refrigerant quality, the more the composition of the circulating refrigerant is suppressed from deviating from the basic composition. When the composition of the circulating refrigerant deviates from the basic composition, the heat exchange performance and controllability of the refrigeration cycle device 100 may be reduced. Therefore, the refrigeration cycle device 100 can suppress the reduction of the heat exchange performance and controllability.

[0076] (4-2) In the refrigeration cycle device 100, the range of refrigerant quality is set so that the change in temperature glide when the composition of the circulating refrigerant deviates from the basic composition is less than a specified value. Specifically, the range of refrigerant quality is set so that the reduction in temperature glide is less than 1K. For the above reasons, the greater the reduction in temperature glide, the more likely the performance of the condenser is to be reduced. Therefore, the refrigeration cycle device 100 can suppress the performance degradation caused by the change in the composition of the circulating refrigerant.

[0077] (4-3) In the refrigeration cycle device 100, a non-azeotropic mixed refrigerant is sealed in the main refrigerant circuit 10. When a refrigerant such as R1123 included in the non-azeotropic mixed refrigerant generates free radicals, it may be converted into other compounds through a disproportionation reaction. The disproportionation reaction is accompanied by a large amount of heat release. Therefore, the reliability of the refrigeration cycle device 100 may be reduced due to the disproportionation reaction caused by the refrigerant included in the circulating refrigerant.

[0078] In the refrigeration cycle device 100, the composition of the circulating refrigerant is suppressed from deviating from the basic composition. Therefore, the increase in the content rate of the refrigerant included in the circulating refrigerant that is easy to cause the disproportionation reaction is suppressed. Therefore, the refrigeration cycle device 100 can suppress the reduction of reliability caused by the disproportionation reaction of the refrigerant.

[0079] (5) Embodiment like Figure 6 As shown, in the refrigeration cycle device 100, the composition of the circulating refrigerant changes according to the refrigerant quality. In order to verify the accuracy of the change in the composition of the circulating refrigerant, an experiment is performed to compare the measured value of the composition of the circulating refrigerant with the predicted value of the composition of the circulating refrigerant as described below. The measured value is obtained by measuring the composition of the circulating refrigerant when the refrigerant quality is a specified value. The predicted value is obtained by calculating the change in the composition of the refrigerant stored in the storage tank based on the gas-liquid equilibrium state.

[0080] (5-1) Structure of the testing machine like Figure 8 As shown, the refrigeration cycle device 200 as a test machine for measuring the actual value of the composition of the circulating refrigerant has Figure 1 The refrigeration cycle device 100 shown in FIG. 2 has a similar structure. However, in the refrigeration cycle device 200, the accumulator 126 is installed 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 reversing valve 22. A liquid level gauge for measuring the volume of the liquid refrigerant stored in the accumulator 126 is installed in the accumulator 126.

[0081] The gas-side refrigerant communication pipe 7 is divided into a first communication pipe 7a and a second communication pipe 7b through the accumulator 126. The first communication pipe 7a connects the gas side of the utilization-side heat exchanger 31 to the accumulator 126. The second communication pipe 7b connects the accumulator 126 to the gas-side stop valve 29. The first sampling valve 61 and the second sampling valve 62 are installed in the second communication pipe 7b. The first sampling valve 61 is installed near the accumulator 126. The second sampling valve 62 is installed near the gas-side stop valve 29.

[0082] (5-2) Operating conditions of the testing machine The refrigeration cycle device 200 used as the test machine is an air conditioning device with a refrigeration capacity of 4.0 kW. The refrigeration cycle device 200 is operated in the refrigeration operation mode. The length of the liquid-side refrigerant communication pipe 6 is 5.0 m. The outer diameter of the liquid-side refrigerant communication pipe 6 is 6.4 mm. The length of the gas-side refrigerant communication pipe 7 is 5.0 m. The outer diameter of the gas-side refrigerant communication pipe 7 is 9.5 mm.

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

[0084] In the main refrigerant circuit 10, after a predetermined amount of refrigerant is initially charged, a predetermined amount of refrigerant is additionally charged so that liquid refrigerant is accumulated in the accumulator 126. When charging the additional refrigerant, parameters related to the humidity of the circulating refrigerant are manually controlled so that the liquid refrigerant is stored in the accumulator 126.

[0085] (5-3) Measurement results The gas refrigerant and circulating refrigerant in the storage tank 126 are sampled, and the composition of the refrigerant is measured by gas chromatography to obtain the measured value of the composition of the circulating refrigerant. The gas refrigerant in the storage tank 126 is sampled from the first sampling valve 61. The circulating refrigerant is sampled from the second sampling valve 62.

[0086] As shown in the following table, the actual measured value of the composition of the gas refrigerant in the storage tank 126, the actual measured value of the composition of the circulating refrigerant, and the predicted value of the composition of the circulating refrigerant are obtained or calculated for Examples 1 to 3, respectively.

[0087] [Table 1]

[0088] In the above table, the refrigerant circulation amount is the weight of the refrigerant circulating in the main refrigerant circuit 10 per hour. The refrigerant filling amount is the weight of the refrigerant filled in the main refrigerant circuit 10 after the additional refrigerant filling. The liquid storage amount is the weight of the liquid refrigerant stored in the storage tank 126. The refrigerant quality is calculated based on the above formula (III) and the following formula (IV). Refrigerant quality = (refrigerant filling amount - liquid storage amount) / refrigerant filling amount... (IV)

[0089] The refrigerant qualities of Examples 1 to 3 are different from each other. In the above table, the measured values ​​and predicted values ​​of the composition are recorded in order of the content rate (mass %) of R32 and the content rate (mass %) of T1234yf.

[0090] The experimental results confirmed that the measured value of the composition of the circulating refrigerant was very close to the predicted value of the composition of the circulating refrigerant. In addition, it was confirmed that the measured value of the composition of the gas refrigerant in the storage tank 126 was almost the same as the measured value of the composition of the circulating refrigerant.

[0091] In addition, it was confirmed that the higher the refrigerant quality, the smaller the difference between the measured value of the R32 content of the circulating refrigerant composition and the R32 content of the basic composition (21.5 mass %). Therefore, it was confirmed that the higher the refrigerant quality, the more the circulating refrigerant composition deviates from the basic composition.

[0092] (6) Modification In the embodiment, the mixed refrigerant sealed in the main refrigerant circuit 10 is R454C. R454C includes 21.5% by mass of R32 and 78.5% by mass of R1234yf. In this case, the content of R32 is limited to 30.0% by mass or less so that the reduction in temperature glide when the composition of the circulating refrigerant deviates from the basic composition is 1K or less. As a result, the refrigerant quality is set to exceed 0.65.

[0093] Next, the setting of the refrigerant quality when the first to third mixed refrigerants, which are mixed refrigerants other than R454C, are sealed in the main refrigerant circuit 10 will be described. The method of determining the range of the refrigerant quality when the first to third mixed refrigerants are used is the same as the method of determining the range of the refrigerant quality when the first to third mixed refrigerants are used. Figure 5 and Figure 6 The method for determining the range of refrigerant quality when using R454C shown is the same.

[0094] (6-1) First mixed refrigerant The first mixed refrigerant includes R1132(E) and R1234yf. The basic composition of the first mixed refrigerant is composed of 23.0 mass% of R1132(E) and 77.0 mass% of R1234yf. The temperature glide when the content of R1132(E) in the first mixed refrigerant is 7.0K. The content of R1132(E) in the first mixed refrigerant when the temperature glide decreases by 1K from 7.0K to 6.0K is 45.0 mass%.

[0095] In this case, the content of R1132(E) is limited to 45.0 mass % or less so that the temperature glide decreases by 1 K or less when the composition of the circulating refrigerant deviates from the basic composition. Therefore, when the first mixed refrigerant is used, the refrigerant quality is set to exceed 0.15.

[0096] (6-2) Second mixed refrigerant The second mixed refrigerant includes R1132(E), R1234yf and R32. The basic composition of the second mixed refrigerant is composed of 22.0 mass% of R1132(E), 56.0 mass% of R1234yf and 22.0 mass% of R32. The temperature glide when the content of R1132(E) in the second mixed refrigerant is 5.3K based on the content of R1132(E) in the second mixed refrigerant (22.0 mass%). The content of R1132(E) in the second mixed refrigerant when the temperature glide is reduced by 1K from 5.3K to 4.3K is 32.0 mass%.

[0097] In this case, the content of R1132(E) is limited to 32.0 mass % or less so that the temperature glide decreases by 1 K or less when the composition of the circulating refrigerant deviates from the basic composition. Therefore, when the second mixed refrigerant is used, the refrigerant quality is set to exceed 0.22.

[0098] (6-3) Third mixed refrigerant The third mixed refrigerant includes R1123 and R1234yf. The basic composition of the third mixed refrigerant is composed of 34.0 mass% of R1123 and 66.0 mass% of R1234yf. The content of R1123 in the third mixed refrigerant is 8.0K when the content of R1123 in the third mixed refrigerant (34.0 mass%) is the basic composition. The content of R1123 in the third mixed refrigerant when the temperature glide is reduced by 1K from 8.0K to 7.0K is 61.0 mass%.

[0099] In this case, the content of R1123 is limited to 61.0 mass % or less so that the temperature glide decreases by 1 K or less when the composition of the circulating refrigerant deviates from the basic composition. Therefore, when the third mixed refrigerant is used, the refrigerant quality is set to exceed 0.12.

[0100] As mentioned above, although embodiment of this disclosure is described, it should be understood that various changes in form and details can be made without departing from the spirit and scope of this disclosure described in the claims. Explanation of symbols

[0101] 10 main refrigerant circuit (refrigerant circuit); 21 compressor; 23 heat exchanger on the heat source side (evaporator, condenser); 25 heat source side expansion valve (expansion mechanism); 26 storage tanks; 31 Utilization side heat exchanger (condenser, evaporator); 70 Control Department; 100 Refrigeration cycle device. Prior art literature Patent Literature

[0102] Patent Document 1: Japanese Patent Application Publication No. 2015-200431.

Claims

1. A refrigeration cycle device (100), characterized in that: include: Compressor (21); Condenser (23); Expansion mechanism (25); Evaporator (31); a storage tank (26); and A refrigerant circuit (10), in which the compressor, the condenser, the expansion mechanism, the evaporator and the storage tank are connected in a ring shape and a mixed refrigerant is sealed. When the amount of the mixed refrigerant sealed in the refrigerant circuit is a first amount and the amount of the liquid refrigerant stored in the storage tank is a second amount, a first value exceeds a value determined based on the mixed refrigerant, wherein the first value is a value obtained by subtracting the second amount from the first amount and dividing the first amount by the first amount, The mixed refrigerant is a non-azeotropic mixed refrigerant.

2. The refrigeration cycle device according to claim 1, characterized in that: The second amount is a product of an effective volume of the storage tank and a saturated liquid density of the mixed refrigerant at a pressure of the mixed refrigerant sucked into the compressor.

3. The refrigeration cycle device according to claim 1 or 2, characterized in that: The mixed refrigerant sealed in the refrigerant circuit has a first composition, When the liquid refrigerant is stored in the storage tank, the mixed refrigerant circulating in the refrigerant circuit has a second composition. T1 is the 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 the saturated liquid temperature of the mixed refrigerant having the second composition after the composition of the mixed refrigerant is changed 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, The first value is set so that a second value obtained by subtracting T1 from T3 is 1K or less.

4. The refrigeration cycle device according to any one of claims 1 to 3, characterized in that: The mixed refrigerant includes 21.5 mass % of R32 and 78.5 mass % of R1234yf, The first value exceeds 0.

65.

5. The refrigeration cycle device according to any one of claims 1 to 3, characterized in that: The mixed refrigerant includes 23.0 mass % of R1132(E) and 77.0 mass % of R1234yf, The first value exceeds 0.

15.

6. The refrigeration cycle device according to any one of claims 1 to 3, characterized in that: The mixed refrigerant includes 22.0 mass % of R1132(E), 56.0 mass % of R1234yf and 22.0 mass % of R32, The first value exceeds 0.

22.

7. The refrigeration cycle device according to any one of claims 1 to 3, characterized in that: The mixed refrigerant includes 34.0 mass % of R1123 and 66.0 mass % of R1234yf, The first value exceeds 0.

12.

8. The refrigeration cycle device according to any one of claims 1 to 7, characterized in that: The refrigeration cycle device further includes a control unit (70) for controlling a parameter related to the humidity of the mixed refrigerant at the inlet of the storage tank.

9. The refrigeration cycle device according to any one of claims 1 to 8, characterized in that: The storage tank has an effective volume below a specified value.

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