JP7309045B2 - refrigeration cycle equipment - Google Patents

Description

The present disclosure relates to a refrigeration cycle device using a non-azeotropic refrigerant mixture.

Conventionally, a refrigeration cycle apparatus using a non-azeotropic refrigerant mixture is known to reduce the global warming potential (GWP). For example, in International Publication No. 2018/139315 (Patent Document 1), in a refrigeration cycle device using a refrigerant having a characteristic of causing a disproportionation reaction (self-decomposition reaction), the estimated discharged refrigerant temperature is equal to or higher than a reference value. It is disclosed that the disproportionation reaction is suppressed by controlling the discharge temperature to be lowered in the region where the

WO2018/139315

In order to control to lower the discharge temperature, it is necessary to lower the frequency of the compressor or increase the opening of the electronic expansion valve. There is a problem of lowering

Further, the disproportionation reaction occurs when conditions such as pressure and temperature are met, but the temperature at which the disproportionation reaction occurs varies depending on the pressure during operation. Therefore, in the technology disclosed in International Publication No. 2018/139315, even in an operable region (conditions in which a disproportionation reaction does not occur), when the discharge refrigerant temperature exceeds the reference value, the discharge temperature is increased. Since it is controlled to lower it, there is a problem that the operating range is narrowed.

The present disclosure discloses a refrigeration cycle apparatus that solves the above-described problems, and the purpose thereof is to reduce the GWP by using a non-azeotropic refrigerant mixture while disproportionating the non-azeotropic refrigerant mixture. It is to achieve both suppression of reaction and suppression of performance deterioration of the refrigeration cycle device.

The present disclosure relates to a refrigeration cycle device in which a non-azeotropic refrigerant mixture is used in a refrigerant circuit. A refrigerant circuit of a refrigeration cycle device includes a compressor, a condenser, an expansion mechanism, and an evaporator. A non-azeotropic refrigerant mixture circulates in the order of a compressor, a condenser, an expansion mechanism, and an evaporator in a refrigerant circuit. Non-azeotropic refrigerant mixtures include R32, CF3I, and HFO1123. The weight ratio of R32, the weight ratio of CF3I, and the weight ratio of HFO1123 in the non-azeotropic mixed refrigerant enclosed in the refrigeration cycle device are represented by W(R32), W(CF3I), and W(HFO1123), respectively. and W(R32) is 43 wt% or less, W(HFO1123) is 14 wt% or more and less than 70 wt%, and W(CF3I) is more than 2 wt% and W(R32) or less.

According to the refrigeration cycle device of the present disclosure, while reducing GWP by using a non-azeotropic refrigerant mixture, it is possible to simultaneously suppress the disproportionation reaction of the non-azeotropic refrigerant mixture and suppress the performance deterioration of the refrigeration cycle device. can be planned.

1 is a functional block diagram showing the configuration of a refrigeration cycle apparatus 100 according to Embodiment 1; FIG. FIG. 4 is a diagram for explaining the boundary at which a disproportionation reaction occurs in a non-azeotropic refrigerant mixture containing HFO1123; FIG. 4 is a diagram for explaining a region where a disproportionation reaction occurs and a pressure threshold in the present embodiment; FIG. 4 is a diagram for explaining how the distribution position of the non-azeotropic mixed refrigerant used in the present embodiment changes when the temperature changes. 4 is a flow chart for explaining processing executed when the compressor of the refrigeration cycle apparatus is started. 4 is a flowchart for explaining a process of lowering the discharge temperature that is executed during operation in Embodiment 1. FIG. 4 is a flow chart for explaining control of the flow regulating valve that is executed during operation in Embodiment 1. FIG. FIG. 10 is a functional block diagram showing the configuration of a refrigeration cycle apparatus 100A according to Embodiment 2; FIG. 10 is a diagram showing positions of refrigerant outlets of a condenser of a refrigeration cycle apparatus 100A according to Embodiment 2; 7 is a flow chart for explaining control of a flow rate adjustment valve that is executed during operation in Embodiment 2. FIG. FIG. 10 is a functional block diagram showing the configuration of a refrigeration cycle device 200 of Embodiment 3 together with the flow of refrigerant in cooling operation; 1 is a ph diagram showing the relationship between enthalpy, pressure, and temperature of a typical non-azeotrope refrigerant mixture. FIG. FIG. 4 is a diagram showing the relationship between the ratio of the weight ratio of R32 to the weight ratio of CF3I and the temperature gradient. FIG. 4 is a diagram showing the relationship between the weight ratio of R32 to the weight ratio of R1234yf and the temperature gradient. FIG. 4 is a diagram showing the relationship between the weight ratio of R32 to the weight ratio of R1234ze(E) and the temperature gradient. 4 is a ph diagram showing changes in the state of a non-azeotropic refrigerant mixture during cooling operation. FIG. FIG. 7 is a functional block diagram showing the configuration of a refrigeration cycle apparatus according to Embodiment 3 together with the flow of refrigerant in heating operation; FIG. 4 is a ph diagram showing changes in the state of a non-azeotropic refrigerant mixture during heating operation. FIG. 18 is a flowchart for explaining an example of control of an expansion valve 4C performed by the control device of FIGS. 11 and 17; FIG. 10 is a flow chart for explaining control of the flow regulating valve that is executed during operation in Embodiment 3. FIG. FIG. 11 is a functional block diagram showing the configuration of a refrigeration cycle device 200A according to Embodiment 4;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

Embodiment 1.
FIG. 1 is a functional block diagram showing the configuration of a refrigeration cycle apparatus 100 according to Embodiment 1. As shown in FIG. As the refrigerating cycle device 100, for example, a PAC (Package Air Conditioner) can be cited. As shown in FIG. 1 , the refrigeration cycle device 100 includes an outdoor unit 110 and an indoor unit 120. As shown in FIG. The outdoor unit 110 includes a compressor 1, a four-way valve 2, an expansion valve LEV1, a heat exchanger 6, an outdoor fan 11, an accumulator ACC, a flow control valve LEV2, a controller 10, a temperature sensor 13T, 14, 15 and a pressure sensor 13P. Indoor unit 120 includes heat exchanger 3 , indoor fan 12 , and temperature sensors 16 and 17 .

It should be noted that temperature sensors 14 and 17 instead of the pressure sensor 13P can be used to detect the composition ratio of the refrigerant by providing temperature detection sensors at locations corresponding to the liquid phase portion and the gas phase portion of the accumulator, respectively. It may be estimated from the pressure.

The refrigeration cycle device 100 uses a non-azeotropic refrigerant mixture in which GWP is reduced by mixing R32, CF ₃ I (hereinafter referred to as CF3I), and HFO1123. HFO1123 is a high-pressure refrigerant with a small GWP (GWP=4) and has a characteristic of having a higher gas density than R32, so we would like to actively use it.

In this specification, the weight ratios of R32, CF3I, and HFO1123 in the non-azeotropic mixed refrigerant enclosed in the refrigeration cycle device 100 are respectively W(R32), W(CF3I), and W(HFO1123). show. Note that the weight ratio may also be referred to as mass ratio. At this time, W(R32) is 43 wt% or less, W(HFO1123) is 14 wt% or more and less than 70 wt%, and W(CF3I) is more than 2 wt% and W(R32) or less. Even if the amount of the non-azeotropic refrigerant mixture used increases with the increase in the number of shipments of the refrigeration cycle device 100, the weight ratio of R32 is set so that the refrigerant regulations (for example, the Montreal Protocol or the F-gas regulation) are satisfied. is 30 wt % or less to further reduce the GWP.

The boiling points of R32, CF3I, and HFO1123 are -52°C, -22.5°C, and -56°C, respectively. HFO 1123 increases the operating pressure of non-azeotropic refrigerant mixtures. By including HFO1123 in the non-azeotropic refrigerant mixture, the volume (stroke volume) of the compressor 1 required to ensure a desired operating pressure can be reduced, so the size of the compressor 1 can be reduced. can. The non-azeotropic refrigerant mixture may contain refrigerants other than R32, CF3I, and HFO1123 (for example, R1234yf, R1234ze(E), R290, or CO ₂ ) as long as the reduction in GWP is not hindered.

The control device 10 includes a CPU (Central Processing Unit) 31, a memory 32 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input/output buffer (not shown) for inputting and outputting various signals, and the like. Consists of The CPU 31 expands the program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program in which processing procedures of the control device 10 are described. The control device 10 controls each device of the refrigeration cycle device 100 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

The control device 10 controls the operating frequency of the compressor 1 so that the temperature inside the indoor unit 120 obtained by the temperature sensor 17 becomes a desired temperature (for example, the temperature set by the user). controls the amount of refrigerant discharged per unit time. The control device 10 controls the degree of opening of the expansion valve LEV1 so that the degree of superheating or degree of supercooling of the non-azeotropic refrigerant mixture falls within a desired range. The control device 10 controls the amount of air blown by the outdoor fan 11 and the indoor fan 12 per unit time. The control device 10 acquires the discharge temperature Td of the non-azeotropic refrigerant mixture discharged from the compressor 1 from the temperature sensor 13T.

The control device 10 controls the four-way valve 2 to switch the circulation direction of the non-azeotropic refrigerant mixture. The control device 10 controls the four-way valve 2 to allow communication between the discharge port of the compressor 1 and the heat exchanger 6 and communication between the heat exchanger 3 and the suction port of the compressor 1 during cooling operation. In the cooling operation, the non-azeotropic refrigerant mixture flows through the compressor 1, the four-way valve 2, the heat exchanger 6, the expansion valve LEV1, the heat exchanger 3, the four-way valve 2, and the accumulator ACC in this order, as indicated by solid arrows in the figure. Circulate. In addition, the control device 10 controls the four-way valve 2 to allow communication between the discharge port of the compressor 1 and the heat exchanger 3 and communication between the heat exchanger 6 and the suction port of the compressor 1 during heating operation. . In the heating operation, the non-azeotropic refrigerant mixture flows through the compressor 1, the four-way valve 2, the heat exchanger 3, the expansion valve LEV1, the heat exchanger 6, the four-way valve 2, and the accumulator ACC in this order, as indicated by the dashed arrows in the figure. Circulate.

Part of the non-azeotropic refrigerant mixture that has flowed into the accumulator ACC is separated into a liquid non-azeotropic refrigerant mixture and a gaseous non-azeotropic refrigerant mixture, and is stored in the accumulator ACC.

In the present embodiment, the control device 10 controls the flow control valve LEV2 so as to suppress the occurrence of disproportionation reaction in the non-azeotropic refrigerant mixture. The flow control valve LEV2 is not particularly limited as long as it can adjust the flow rate, but an electronic expansion valve can be used. HFO1123 refrigerant has the property of causing a disproportionation reaction (self-decomposition reaction). Disproportionation reactions occur when the temperature and pressure of the refrigerant are high. However, the boundary temperature and boundary pressure change with the weight ratio of HFO1123 in the refrigerant.

FIG. 2 is a diagram for explaining the boundary at which the disproportionation reaction of the non-azeotropic refrigerant mixture containing HFO1123 occurs. FIG. 2 shows the boundary where the disproportionation reaction occurs when the weight percent of HFO1123 in the non-azeotropic refrigerant mixture is 70 wt %.

Since the disproportionation reaction occurs when the three conditions of high pressure, high temperature, and the presence of external energy overlap, the location is the compressor 1 in the refrigeration cycle apparatus. Therefore, if the discharge temperature Td of the compressor 1 is lowered, the disproportionation reaction can be suppressed.

However, in the technology disclosed in International Publication No. 2018/139315, the discharge temperature is set as a threshold even in an operable region (conditions in which a disproportionation reaction does not occur) when the refrigerant temperature exceeds a preset temperature. It is controlled to be lower than the value Td1. Therefore, as shown in FIG. 2, the operating range is narrowed. That is, in the low pressure region, the refrigeration cycle device is controlled to lower the discharge temperature even though no disproportionation reaction occurs.

As a result, it is necessary to lower the frequency of the compressor or increase the degree of opening of the electronic expansion valve.

In the present embodiment, the operating range of the refrigeration cycle device is expanded beyond the operable range shown in FIG. operation is carried out.

FIG. 3 is a diagram for explaining the region where the disproportionation reaction occurs and the pressure threshold in the present embodiment.

As shown in FIG. 3, the boundary of the disproportionation reaction generation region is determined by pressure and temperature. For example, when the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture is 70 wt %, the boundary line BD1 is such that the temperature decreases as the pressure increases, and the pressure decreases as the temperature increases.

In the present embodiment, the pressure threshold value Pth is determined according to the blowout temperature Td of the compressor. For example, when the weight ratio of HFO1123 is 70 wt %, pressure threshold Pth1 is determined according to boundary line BD1.

Since the pressure threshold value Pth is determined in accordance with the blow-out temperature Td in this way, the conventionally inoperable range shown in FIG. 2 can be changed to the operable range.

In addition, when the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture changes, the pressure and temperature critical points at which the disproportionation reaction occurs also change. When the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture decreases, the boundary line moves to the upper right in FIG. 3 so that the operable region widens as indicated by boundary line BD3 (weight ratio is 65 wt %).

Conversely, when the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture increases, the boundary line is directed to the lower left in FIG. to move.

That is, when the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture is lowered, the operable region can be widened. In order to reduce the weight ratio of HFO1123, it is necessary to increase the weight ratio of other refrigerants. For example, by increasing the weight ratio of R32 instead of decreasing the weight ratio of HFO1123, the disproportionation reaction can be suppressed and the operable region can be widened.

At this time, it was found that the disproportionation reaction suppressing effect was higher when CF3I and R32 were mixed together at the same ratio than when R32 was mixed alone. That is, CF3I has the effect of suppressing the disproportionation reaction of the HFO1123 refrigerant. For example, when the CF3I mass ratio is more than 2 wt% with respect to the HFO1123 mass ratio of 60%, the disproportionation reaction is suppressed, and a CF3I mass ratio of about 5% has a sufficient suppression effect.

Therefore, by reducing the weight ratio of HFO1123 in the non-azeotropic refrigerant mixture and increasing the CF3I mass ratio in the compressor 1 where the disproportionation reaction is likely to occur, the operable region can be further expanded, and the refrigeration cycle device can be operated. Performance deterioration can be prevented.

FIG. 4 is a diagram for explaining how the distribution position of the non-azeotropic refrigerant mixture used in this embodiment changes when the temperature changes.

CF3I has a liquid density about 2.2 times higher than that of HFO1123. CF3I has a higher boiling point than HFO1123. FIG. 4 shows the refrigerant relationship estimated from the refrigerant density relationship in each temperature state. As shown in FIG. 4(a), when the temperature is 10° C. and the liquid refrigerant is in the liquid refrigerant state, CF3I is accumulated at the bottom, the mixed liquid of R32 and HFO1123 is positioned above it, and the refrigerating machine oil is positioned at the top. As shown in FIG. 4(b), when the temperature is 65° C. and the liquid refrigerant is in the liquid refrigerant state, CF3I is accumulated at the bottom, the refrigerating machine oil is positioned above it, and the mixture of R32 and HFO1123 is positioned at the top. As shown in FIG. 4(c), in the gas refrigerant state, refrigerating machine oil accumulates at the bottom, HFO1123 is positioned above it, R32 is positioned further above that, and CF3I is positioned at the top.

That is, CF3I, which suppresses the disproportionation reaction, tends to accumulate in the lower part when the liquid refrigerant is used, but tends to accumulate in the upper part when the gas refrigerant is used.

In the first embodiment, the fact that CF3I tends to accumulate at the lowest portion of the liquid phase portion of a container or the like in which liquid refrigerant is accumulated is used to allow refrigerant with a high CF3I ratio to flow into the compressor 1 from that portion.

Specifically, the liquid refrigerant is injected into the suction portion of the compressor 1 from the lowest portion of the accumulator ACC near the threshold, which is the boundary of the disproportionation reaction occurrence region. As a result, the refrigerant having a high CF3I ratio flows to the compressor 1, thereby suppressing the disproportionation reaction.

The shape of the accumulator ACC is preferably 1.1 times or more the height of the diameter. This makes it easier for the liquid refrigerant to stay, so that the high-concentration refrigerant tends to exist at the bottom. Any container having a function of separating gas and liquid and facilitating retention of the liquid refrigerant may be used without being limited to the accumulator ACC.

FIG. 5 is a flow chart for explaining the process executed when the compressor of the refrigeration cycle apparatus is started.

In the refrigeration cycle apparatus of the present embodiment, abnormal operation is detected at startup. For example, when the flow path of the refrigerant is clogged or the stop valve (not shown) on the indoor unit side is closed due to failure or the like, the refrigerant does not circulate well, resulting in abnormal operation. Therefore, as shown in the following flow chart, it is checked at the start of operation whether the temperature of the refrigerant in the heat exchanger changes correctly as the discharge temperature rises, in addition to not increasing the frequency all at once at the start of operation. Note that the step is simply described as S below.

First, in S1, the control device 10 starts the operation of the compressor 1 at an initial operating frequency lower than that during normal operation. In S2, it is determined whether or not the cooling operation is being performed.

In the case of the cooling operation (YES in S2), in S3, the refrigerant temperature Tm6 of the heat exchanger 6 acting as a condenser rises by ΔT1 or more compared to before the start of operation, and the temperature of the heat exchanger 3 acting as an evaporator rises. It is determined whether or not the coolant temperature Tm3 has decreased by ΔT2 or more from the level before the start of operation.

If the refrigerant temperatures Tm6 and Tm3 have changed correctly (YES in S3), it is determined in S4 that the refrigeration cycle apparatus 100 is operating normally, the control is returned to the main routine, and then the suppression of the operating frequency is released. operation is continued.

If the cooling operation is not performed (NO in S2), in S5, the refrigerant temperature Tm3 of the heat exchanger 3 acting as a condenser rises by ΔT3 or more compared to before the start of operation, and the refrigerant temperature of the heat exchanger 6 acting as an evaporator rises. It is determined whether or not Tm6 has decreased by ΔT4 or more from before the start of operation.

If the refrigerant temperatures Tm6 and Tm3 have changed correctly (YES in S5), it is determined in S6 that the refrigeration cycle apparatus 100 is operating normally, the control is returned to the main routine, and then the suppression of the operating frequency is released. operation is continued.

On the other hand, if the refrigerant temperatures Tm6 and Tm3 have not changed correctly (NO in S3 or NO in S5), it is determined in S7 that the refrigeration cycle device 100 may be operating abnormally, and in S8 the refrigeration cycle device 100 is operated. is stopped and the process ends.

FIG. 6 is a flowchart for explaining the process of lowering the discharge temperature that is executed during operation in the first embodiment. The processing shown in FIG. 6 is called at regular time intervals by a main routine (not shown) that comprehensively controls the refrigeration cycle apparatus 100 .

As shown in FIG. 6, in S101, the control device 10 determines whether or not the discharge temperature Td is lower than the reference temperature τ1. If the discharge temperature Td is lower than the reference temperature τ1 (YES in S101), the control device 10 returns the process to the main routine. If the discharge temperature Td is equal to or higher than the reference temperature τ1 (NO in S101), the control device 10 advances the process to S102.

The controller 10 reduces the operating frequency of the compressor 1 in S102, and advances the process to S103. In S103, the control device 10 increases the amount of air blown to the heat exchanger functioning as a condenser, and advances the process to S104. In the cooling operation, the controller 10 increases the amount of air blown by the outdoor fan 11 per unit time in S103. In the heating operation, the control device 10 increases the blowing volume of the indoor fan 12 in S103. The controller 10 increases the degree of opening of the expansion valve LEV1 in S104 and returns the process to the main routine. In order to reduce the discharge temperature, it is more preferable to increase the amount of air blown not only in the heat exchanger of the condenser but also in the heat exchanger of the evaporator.

It should be noted that at least one of S102 to S104 need only be performed, and not all of S102 to S104 need to be performed. Also, S102 to S104 do not have to be performed in the order shown in FIG.

FIG. 7 is a flowchart for explaining control of the flow rate adjustment valve that is executed during operation in the first embodiment. The processing shown in FIG. 7 is called at regular time intervals by a main routine (not shown) that comprehensively controls the refrigeration cycle apparatus 100 . First, in S11, the control device 10 calculates pressure threshold values Pth1 and Pth2 based on the discharge temperature Td. The pressure thresholds Pth1 and Pth2 are calculated by, for example, setting the pressure on the boundary line BD1 at the weight ratio of HFO1123 of 70 wt% in FIG. The pressure on BD2 can be set to a pressure threshold Pth2.

The pressure threshold Pth1 is preferably a boundary condition at a weight ratio of HFO1123 of 70 wt%, and more preferably a boundary condition at a weight ratio of HFO1123 of 75 wt%. In the case of a weight ratio of 75 wt%, even if it is actually within the usable area, a margin for the boundary is ensured and it is determined that it cannot be used.

Subsequently, in S12, the control device 10 determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1.

If Pd<Pth1 does not hold (NO in S12), in S16, the control device 10 opens the flow control valve LEV2 so that the liquid refrigerant with a high concentration of CF3I is sucked into the compressor 1 from the bottom of the accumulator ACC. degree A is increased by the first set amount Δα1. As a result, the concentration of CF3I in the non-azeotropic mixed refrigerant sucked into the compressor 1 increases, and the concentration of HFO1123 decreases. Then, the map that defines the threshold value Pth1 shown in FIG. 3 shifts in the direction of the arrow in FIG. 3, so that if the temperature Td remains the same, the pressure threshold value Pth1 increases. Such a relationship between the change in threshold value and the opening of LEV2 is experimentally obtained in advance and stored in the memory of control device 10 . Therefore, in S16, the control device 10 increases the opening degree A of the flow control valve LEV2 and increases the pressure threshold value Pth1. That is, the boundary line BD1 in FIG. 3 is moved according to the opening degree A. Thereafter, pressure threshold values Pth1 and Pth2 are calculated again in S11.

When Pd<Pth1 is established (YES in S12), in S13, the control device 10 decreases the opening degree A of the flow rate regulating valve LEV2 by the second set amount Δα2. The second set amount Δα2 is set to a value smaller than the first set amount Δα1. At this time as well, the pressure thresholds Pth1 and Pth2 are updated based on the relationship between the predetermined opening A and the boundary line BD1 in FIG. 3 as the opening A of the flow control valve LEV2 decreases.

Then, in S14, the control device 10 determines whether or not the discharge pressure Pd is higher than the pressure threshold value Pth2. Note that the pressure threshold Pth2 is set lower than the pressure threshold Pth1 as shown in FIG.

If Pd>Pth2 does not hold (NO in S14), the control device 10 executes the process of S13 again. If Pd>Pth2 holds (YES in S14), in S15, the control device 10 determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1.

If Pd<Pth1 does not hold (NO in S15), in S16, the controller 10 opens the flow control valve LEV2 so that the liquid refrigerant with a high concentration of CF3I is sucked into the compressor 1 from the bottom of the accumulator ACC. The degree A is increased by the first set amount Δα1, and the pressure threshold values Pth1 and Pth2 are calculated again in S11.

If Pd<Pth1 is established (YES in S15), the opening of the flow rate regulating valve LEV2 is set to an appropriate opening, and control is returned to the main routine.

As described above, the refrigeration cycle apparatus 100 shown in Embodiment 1 can inject a liquid-phase refrigerant having a high CF3I concentration into the suction port of the compressor 1, so that the weight ratio of HFO 1123 in the compressor 1 is It is possible to suppress the occurrence of the disproportionation reaction while lowering the

In addition, as shown in FIG. 4(c), in the gas phase, the concentration of CF3I is higher in the upper part, so the intake port of the pipe BL in FIG. may be injected into the suction port of the compressor 1.

Embodiment 2.
In Embodiment 1, the accumulator ACC provided upstream of the suction portion of the compressor 1 is used as a place where the liquid refrigerant is stored, and the refrigerant with high CF3I concentration is taken out. However, it may be anywhere else where liquid refrigerant is present, such as, for example, the suction muffler or the bottom of the condenser. Embodiment 2 will explain an example in which the liquid refrigerant is returned to the compressor from the bottom of the condenser.

FIG. 8 is a functional block diagram showing the configuration of a refrigeration cycle apparatus 100A according to Embodiment 2. As shown in FIG. As shown in FIG. 8, the refrigeration cycle device 100A includes an outdoor unit 110A and an indoor unit 120. As shown in FIG. Indoor unit 120 has the same configuration as that of the first embodiment shown in FIG. 1, and therefore description thereof will not be repeated.

The outdoor unit 110A includes a compressor 1, a four-way valve 2, an expansion valve LEV1, a heat exchanger 6, an outdoor fan 11, a controller 10, temperature sensors 13T, 14, 15, and a pressure sensor 13P. include.

The non-azeotropic refrigerant mixture enclosed in the refrigeration cycle device 100A is the same as in the first embodiment. The state of the four-way valve 2 and the direction of circulation of the refrigerant during cooling and heating are basically the same as in the first embodiment. Therefore, the description of these will not be repeated.

In Embodiment 2, the outdoor unit 110A includes a first bypass passage BL1 that communicates between the intermediate portion of the heat exchanger 6 and the suction port of the compressor 1, and a flow rate adjustment valve LEV2 that is provided in the first bypass passage BL1. -1, a second bypass passage BL2 that communicates between the intermediate portion of the heat exchanger 3 and the suction port of the compressor 1, and a flow control valve LEV2-2 provided in the second bypass passage BL2.

FIG. 9 is a schematic diagram showing the positions of the refrigerant outlets of the condenser of the refrigeration cycle apparatus 100A according to Embodiment 2. As shown in FIG. In the second embodiment, the heat exchangers 3 and 6 are provided with an intermediate refrigerant outlet in addition to the usual refrigerant inlet and refrigerant outlet. The refrigerant intermediate outlet is provided at a position where the liquid-phase refrigerant can be extracted from the portion where the liquid-phase refrigerant stays when each of the heat exchangers 3 and 6 is used as a condenser. Specifically, when the refrigerant flow path in the condenser is divided into two or more upper and lower paths as shown in FIG. be provided.

The control of FIGS. 5 and 6 is similarly executed in the second embodiment. In Embodiment 2, the control of the flow control valve LEV2 is slightly different. FIG. 10 is a flow chart for explaining control of the flow rate adjustment valve that is executed during operation in the second embodiment. The process shown in FIG. 10 is called at regular time intervals by a main routine (not shown) that performs integrated control of the refrigeration cycle apparatus 100A.

The flowchart shown in FIG. 10 executes the processes of S13A and S16A instead of the processes of S13 and S16 in the flowchart shown in FIG.

First, in S11, the control device 10 calculates pressure threshold values Pth1 and Pth2 based on the discharge temperature Td. Calculation of pressure thresholds Pth1 and Pth2 is the same as in the first embodiment, and thus description thereof will not be repeated.

Subsequently, in S12, the control device 10 determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1.

If Pd<Pth1 does not hold (NO in S12), in S16A, the control device 10 is connected to the condenser so that the liquid refrigerant having a high concentration of CF3I is sucked into the compressor 1 from the bottom of the condenser. The degree of opening A of the flow rate control valve LEV2, which is present, is increased by the first set amount Δα1. As a result, the concentration of CF3I in the non-azeotropic mixed refrigerant sucked into the compressor 1 increases, and the concentration of HFO1123 decreases. Then, the map that defines the threshold value Pth1 shown in FIG. 3 shifts in the direction of the arrow in FIG. 3, so that if the temperature Td remains the same, the pressure threshold value Pth1 increases. The relationship between the change in the threshold value and the degree of opening of the flow control valve LEV2 is experimentally obtained in advance and stored in the memory of the control device 10 . Therefore, in S16A, the control device 10 increases the opening degree A of the flow control valve LEV2 and increases the pressure threshold value Pth1. That is, the boundary line BD1 in FIG. 3 is moved according to the opening degree A. Thereafter, pressure threshold values Pth1 and Pth2 are calculated again in S11.

When Pd<Pth1 is established (YES in S12), in S13A, the control device 10 decreases the opening degree A of the flow control valve LEV2 connected to the condenser by the second set amount Δα2. The second set amount Δα2 is set to a value smaller than the first set amount Δα1. At this time as well, the pressure thresholds Pth1 and Pth2 are updated based on the relationship between the predetermined opening A and the boundary line BD1 in FIG. 3 as the opening A of the flow control valve LEV2 decreases.

Since the heat exchanger 6 functions as a condenser during cooling, the flow control valve LEV2-1 corresponds to the flow control valve LEV2 in S16A and S13A. In this case, the flow control valve LEV2-2 connected to the heat exchanger 3, which is the evaporator, is closed.

Since the heat exchanger 3 functions as a condenser during heating, the flow control valve LEV2-2 corresponds to the flow control valve LEV2 in S16A and S13A. In this case, the flow control valve LEV2-1 connected to the heat exchanger 6, which is the evaporator, is closed.

Then, in S14, the control device 10 determines whether or not the discharge pressure Pd is higher than the pressure threshold value Pth2. Note that the pressure threshold Pth2 is set lower than the pressure threshold Pth1 as shown in FIG. When the LEV2 is closed as a result of the process of S13A, the process of S15 is performed.

If Pd>Pth2 does not hold (NO in S14), the control device 10 executes the process of S13A again. If Pd>Pth2 holds (YES in S14), in S15, the control device 10 determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1.

If Pd<Pth1 does not hold (NO in S15), in S16A, the controller 10 opens the flow control valve LEV2 so that the liquid refrigerant with a high concentration of CF3I is sucked into the compressor 1 from the bottom of the condenser. The degree A is increased by the first set amount Δα1, and the pressure threshold values Pth1 and Pth2 are calculated again in S11.

If Pd<Pth1 is established (YES in S15), the opening of the flow rate regulating valve LEV2 is set to an appropriate opening, and control is returned to the main routine.

As described above, in the refrigerating cycle device 100A according to the second embodiment, as in the refrigerating cycle device 100 according to the first embodiment, liquid-phase refrigerant having a high CF3I concentration is injected into the suction port of the compressor 1. Therefore, the weight ratio of HFO 1123 in the compressor 1 can be lowered, and the occurrence of disproportionation reaction can be suppressed.

Embodiment 3.
FIG. 11 is a functional block diagram showing the configuration of the refrigeration cycle device 200 of Embodiment 3 together with the flow of the refrigerant in the cooling operation. The configuration of the refrigerating cycle device 200 is a configuration in which the outdoor unit 110 of the refrigerating cycle device 100 in FIG. 1 is replaced with an outdoor unit 210 .

Indoor unit 120 includes heat exchanger 3 and indoor fan 12 . The outdoor unit 210 includes a compressor 1, a four-way valve 2, an expansion valve 4A, an expansion valve 4B, a receiver 5, a heat exchanger 6, an outdoor fan 11, a controller 10, and a temperature sensor 13. include. The receiver 5 is a refrigerant container that stores surplus refrigerant.

Outdoor unit 210 further includes an expansion valve 4C, a three-way valve 8, an internal heat exchanger 7, and temperature sensors 9A-9C.

As shown in FIG. 11, the internal heat exchanger 7 is connected between the receiver 5 and the expansion valve 4C and between the four-way valve 2 and the receiver 5. As shown in FIG. The three-way valve 8 is connected between the expansion valve 4C and the flow path FP1 connecting the heat exchanger 3 and the expansion valve 4B. Also, the three-way valve 8 is connected between the expansion valve 4C and the flow path FP2 connecting the expansion valve 4A and the heat exchanger 6 . The cooling operation of the refrigeration cycle device 200 is started with the expansion valve 4C closed. The connection position of the internal heat exchanger 7 is any connection position through which the non-azeotropic refrigerant mixture flowing between the outlet of the heat exchanger 3, the four-way valve 2, and the suction port of the compressor 1 passes. It may be in a connected position, for example connected between the receiver 5 and the expansion valve 4C and between the receiver 5 and the suction of the compressor 1 .

In FIG. 11, the control device 10 controls the operating frequency of the compressor 1, thereby controlling the amount of refrigerant discharged by the compressor 1 per unit time so that the temperature inside the indoor unit 120 reaches a desired temperature. . The control device 10 controls the degree of opening of the expansion valves 4A and 4B so that the degree of superheating or degree of supercooling of the non-azeotropic refrigerant mixture falls within a desired range. The control device 10 controls the amount of air blown by the outdoor fan 11 and the indoor fan 12 per unit time.

The control device 10 acquires the discharge temperature Td of the non-azeotropic refrigerant mixture discharged from the compressor 1 from the temperature sensor 13T. The control device 10 acquires the temperature T91 of the gaseous non-azeotropic refrigerant mixture in the receiver 5 from the temperature sensor 9A. The control device 10 acquires the temperature T92 of the liquid non-azeotropic refrigerant mixture in the receiver 5 from the temperature sensor 9B. The control device 10 acquires the temperature T93 of the non-azeotropic refrigerant mixture flowing between the internal heat exchanger 7 and the expansion valve 4C from the temperature sensor 9C.

Although FIG. 11 shows the case where the temperature sensors 9A and 9B are installed on the side surface of the receiver 5, the positions where the temperature sensors 9A and 9B are installed are not limited to the side surfaces of the receiver 5. The temperature sensor 9A may be installed at any position as long as it can measure the temperature of the gaseous non-azeotropic refrigerant mixture in the receiver 5. For example, the temperature sensor 9A may be installed on the ceiling or on the upper surface of the receiver 5. may be Further, the temperature sensor 9B may be installed at any position as long as it can measure the temperature of the liquid non-azeotropic refrigerant mixture in the receiver 5. For example, the temperature sensor 9B may be installed at the bottom or bottom of the receiver 5. may be

In the cooling operation, the control device 10 controls the four-way valve 2 to communicate the discharge port of the compressor 1 and the heat exchanger 6 and communicate the heat exchanger 3 and the internal heat exchanger 7 in the cooling operation. Let The control device 10 controls the three-way valve 8 to connect the expansion valve 4C to the flow path FP1.

In cooling operation, the non-azeotropic mixed refrigerant is a compressor 1, a four-way valve 2, a heat exchanger 6, an expansion valve 4A, a receiver 5, an expansion valve 4B, a heat exchanger 3, a four-way valve 2, an internal heat exchanger 7, and It circulates in the order of the receiver 5 . A part of the non-azeotropic refrigerant mixture that has flowed into the receiver 5 from the expansion valve 4</b>A is separated into a liquid non-azeotropic refrigerant mixture and a gaseous non-azeotropic refrigerant mixture, and is stored in the receiver 5 . When the expansion valve 4</b>C is open, the gaseous non-azeotropic refrigerant mixture in the receiver 5 is cooled by the internal heat exchanger 7 and then guided to the flow path FP<b>1 .

The height H1 of the end of the refrigerant outlet through which the refrigerant is discharged from the receiver 5 toward the internal heat exchanger 7 is adjusted to be near the liquid surface of the liquid refrigerant. The relationship between the height H0 and the height H1 of the end portion of the refrigerant outlet that discharges the refrigerant from the receiver 5 toward the expansion valve 4B is H1>H0.

Preferably, when the height from the bottom surface to the top surface of the receiver 5 is 100%, 30%≤H1≤70%. In this way, when discharging the liquid refrigerant as shown in FIG. 4B, the mixed refrigerant of HFO1123 and R32 is mainly discharged, and as shown in FIG. , a gaseous refrigerant with a high HFO1123 concentration is discharged.

The node N1 is a node through which the non-azeotropic refrigerant mixture flowing between the compressor 1 and the four-way valve 2 passes. The node N2 is a node through which the non-azeotropic refrigerant mixture flowing between the heat exchanger 6 and the expansion valve 4A passes. The three-way valve 8 and the flow path FP2 communicate with the three-way valve 8 at the node N2. The node N3 is a node through which the non-azeotropic refrigerant mixture flowing between the expansion valve 4A and the receiver 5 passes.

The node N4 is a node through which the non-azeotropic refrigerant mixture flowing between the receiver 5 and the expansion valve 4B passes. A node N5 is a node through which the non-azeotropic refrigerant mixture flowing between the expansion valve 4B and the heat exchanger 3 passes. The flow path FP1 communicates with the three-way valve 8 at the node N5. A node N6 is a node through which the non-azeotropic refrigerant mixture flowing between the four-way valve 2 and the internal heat exchanger 7 passes. A node N7 is a node through which the non-azeotropic refrigerant mixture flowing between the internal heat exchanger 7 and the receiver 5 passes. A node N8 is a node through which the refrigerant flowing between the receiver 5 and the compressor 1 passes.

A node N9 is a node through which the non-azeotropic refrigerant mixture flowing between the receiver 5 and the internal heat exchanger 7 passes. The node N10 is a node through which the non-azeotropic refrigerant mixture flowing between the internal heat exchanger 7 and the expansion valve 4C passes. The node N11 is a node through which the non-azeotropic refrigerant mixture flowing between the three-way valve 8 and the flow path FP1 passes. The node N12 is a node through which the non-azeotropic refrigerant mixture flowing between the three-way valve 8 and the flow path FP2 passes.

The control of FIGS. 5 and 6 is similarly executed in the third embodiment.
Here, the temperature gradient in the two-phase region of the non-azeotropic refrigerant mixture will be described. FIG. 12 is a ph diagram showing the relationship between enthalpy, pressure, and temperature of a typical non-azeotrope refrigerant mixture. In FIG. 12, curves LC and GC represent the saturated liquid line and saturated vapor line, respectively. The saturated liquid line and the saturated vapor line are connected at the critical point CP. Points LP and GP on the saturated liquid line LC represent points on the saturated liquid line and saturated vapor line at the pressure P1, respectively. FIG. 12 shows isotherms of temperatures T1 and T2 (<T1).

As shown in FIG. 12, there is a temperature gradient of T1-T2 between points GP and LP. Non-azeotropic refrigerant mixtures sometimes have the property that the temperature decreases as the enthalpy decreases in the gas-liquid two-phase state (the region between the saturated liquid line LC and the saturated vapor line GC) under the same pressure. As the temperature gradient increases, the temperature of the non-azeotropic refrigerant mixture flowing into the heat exchanger 6 that functions as an evaporator in the heating operation decreases, and the heat exchanger 6 becomes more susceptible to frost formation. As a result, the performance of the refrigeration cycle device 100 may deteriorate.

Therefore, in the refrigerating cycle device 200, the temperature gradient is suppressed by setting the weight ratio of CF3I in the non-azeotropic mixed refrigerant enclosed in the refrigerating cycle device 200 to be equal to or lower than the weight ratio of R32.

FIG. 13 is a diagram showing the relationship between the ratio of the weight ratio of R32 to the weight ratio of CF3I and the temperature gradient. As shown in FIG. 13, when the weight ratio of CF3I is greater than the weight ratio of R32 (the ratio of the weight ratio of R32 to the weight ratio of CF3I is less than 1.0), the temperature gradient of the non-azeotropic refrigerant mixture cannot be ignored. . On the other hand, by setting the weight ratio of CF3I to be equal to or lower than the weight ratio of R32 (the ratio of the weight ratio of R32 to the weight ratio of CF3I is 1.0 or more), the temperature gradient can be substantially eliminated.

As a result, local frost formation on the evaporator is less likely to occur, and the operation efficiency of the refrigeration cycle apparatus can be improved by lengthening the interval between defrosting operations.

In order to reduce the GWP or suppress the disproportionation reaction, it is effective to reduce the weight ratio of HFO1123. be done.

FIG. 14 is a diagram showing the relationship between the weight ratio of R32 to the weight ratio of R1234yf and the temperature gradient. As shown in FIG. 14, by setting the ratio of the weight ratio of R32 to the weight ratio of R1234yf to 87/13, the temperature gradient can be substantially eliminated as in the case of mixing CF3I.

FIG. 15 is a diagram showing the relationship between the ratio of the weight ratio of R32 to the weight ratio of R1234ze(E) and the temperature gradient. As shown in FIG. 15, by setting the ratio of the weight ratio of R32 to the weight ratio of R1234ze(E) to 96.2/3.8, the temperature gradient can be substantially eliminated as in the mixing of CF3I.

FIG. 16 is a ph diagram showing changes in the state of the non-azeotropic refrigerant mixture during cooling operation. Each state shown in FIG. 16 corresponds to each state of the non-azeotropic refrigerant mixture at nodes N1 to N11 in FIG. State C1 represents the state of the non-azeotropic refrigerant mixture flowing between the expansion valve 4B and the node N5.

11 and 16, the process from the state of node N8 to the state of node N1 represents the adiabatic compression process by compressor 1. FIG. The temperature of the non-azeotropic refrigerant mixture in the state of the node N1 is measured by the temperature sensor 13 as the discharge temperature Td. The process from the state of node N1 to the state of node N2 represents the condensation process by heat exchanger 6. FIG. The process from the state of the node N2 to the state of the node N3 represents the decompression process by the expansion valve 4A. The state of node N4 is the state of the saturated liquid flowing out from the receiver 5, which is shown on the saturated liquid line in FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N4 is measured as temperature T92 by temperature sensor 9B. The process from the state of the node N4 to the state C1 represents the decompression process by the expansion valve 4B.

The ph diagram of FIG. 16 shows the case where the gas refrigerant is discharged to the node N9. The state of node N9 is the state of saturated steam flowing out from receiver 5, and is shown on the saturated steam line in FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N9 is measured by temperature sensor 9A as temperature T91 (>T92). The process from the state of node N9 to the state of node N10 represents the cooling process by internal heat exchanger 7. FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N10 is measured by temperature sensor 9C as temperature T93 (<T92). The process from the state of the node N10 to the state of the node N11 represents the pressure reduction process by the expansion valve 4C. The enthalpy of the state of node N11 is less than the enthalpy of state C1. Therefore, the enthalpy at the node N5 where the non-azeotropic refrigerant mixture at the node N11 joins the non-azeotropic refrigerant mixture at the state C1 is greater than the enthalpy at the node N11 and smaller than the enthalpy at the state C1.

The process from the state of node N5 to the state of node N6 represents the vaporization process by heat exchanger 3 . In the process from the state of node N6 to the state of node N7, the non-azeotropic refrigerant mixture passing through internal heat exchanger 7 absorbs heat from the non-azeotropic refrigerant mixture in the state of node N9. Therefore, the enthalpy of the state of node N7 is greater than the enthalpy of the state of node N6.

In the refrigeration cycle device 100, the enthalpy of the non-azeotropic refrigerant mixture flowing into the heat exchanger 3 functioning as an evaporator in the cooling operation (the enthalpy in the state of the node N5) is the same as the non-azeotropic refrigerant mixture flowing out from the expansion valve 4B. is reduced by the internal heat exchanger 7 than the enthalpy of (the enthalpy of state C1). Further, the enthalpy of the non-azeotropic refrigerant mixture sucked into the compressor 1 (enthalpy in the state of node N8) is changed by the internal heat exchanger 7 to the enthalpy of the non-azeotropic refrigerant mixture flowing out of the heat exchanger 3 (node N6 state enthalpy). Therefore, the difference between the enthalpy of the non-azeotropic refrigerant mixture flowing into the heat exchanger 3 and the enthalpy of the non-azeotropic refrigerant mixture sucked into the compressor 1 increases. As a result, the cooling operation efficiency of the refrigeration cycle device 100 can be improved.

FIG. 17 is a functional block diagram showing the configuration of a refrigeration cycle apparatus according to Embodiment 3 together with the flow of refrigerant in heating operation. The heating operation of the refrigeration cycle device 200 is also started with the expansion valve 4C closed. In the heating operation, the control device 10 allows the discharge port of the compressor 1 and the heat exchanger 3 to communicate with each other, and also allows the heat exchanger 6 and the internal heat exchanger 7 to communicate with each other. The control device 10 controls the three-way valve 8 to connect the expansion valve 4C to the flow path FP2.

In the heating operation, the non-azeotropic mixed refrigerant is the compressor 1, the four-way valve 2, the heat exchanger 3, the expansion valve 4B, the receiver 5, the expansion valve 4A, the heat exchanger 6, the four-way valve 2, the internal heat exchanger 7, and It circulates in the order of the receiver 5 . A portion of the non-azeotropic refrigerant mixture that has flowed into the receiver 5 from the expansion valve 4B is separated into a liquid non-azeotropic refrigerant mixture and a gaseous non-azeotropic refrigerant mixture, and is stored in the receiver 5 .

FIG. 18 is a ph diagram showing changes in the state of the non-azeotropic refrigerant mixture during heating operation. Each state shown in FIG. 18 corresponds to each state of the non-azeotropic refrigerant mixture at nodes N1 to N10 and N12 in FIG. State C2 represents the state of the non-azeotropic refrigerant mixture flowing between the expansion valve 4A and the node N2.

17 and 18, the process from the state of node N8 to the state of node N1 represents the adiabatic compression process by compressor 1. FIG. The temperature of the non-azeotropic refrigerant mixture in the state of the node N1 is measured by the temperature sensor 13 as the discharge temperature Td. The process from the state of node N1 to the state of node N5 represents the condensation process by heat exchanger 3 . A process from the state of the node N5 to the state of the node N4 represents the pressure reduction process by the expansion valve 4B. The state of node N3 is the state of the saturated liquid flowing out from the receiver 5, which is shown on the saturated liquid line in FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N3 is measured as temperature T92 by temperature sensor 9B. The process from the state of node N3 to state C2 represents the pressure reduction process by the expansion valve 4A.

The ph diagram of FIG. 18 shows the case where the gas refrigerant is discharged to the node N9. The state of node N9 is the state of saturated steam flowing out from receiver 5, and is shown on the saturated steam line in FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N9 is measured by temperature sensor 9A as temperature T91 (>T92). The process from the state of node N9 to the state of node N10 represents the cooling process by internal heat exchanger 7. FIG. The temperature of the non-azeotropic refrigerant mixture in the state of node N10 is measured by temperature sensor 9C as temperature T93 (<T92). The process from the state of node N10 to node N12 represents the pressure reduction process by the expansion valve 4C. The enthalpy of the state of node N12 is less than the enthalpy of state C2. Therefore, the enthalpy in the state of node N2, where the non-azeotropic refrigerant mixture in state C2 joins with the non-azeotropic refrigerant mixture in state N12, is greater than the enthalpy in node N12 and smaller than the enthalpy in state C2.

The process from the state of node N2 to the state of node N6 represents the evaporation process by heat exchanger 6. FIG. In the process from the state at node N6 to the state at node N7, the non-azeotropic refrigerant mixture absorbs heat from the non-azeotropic refrigerant mixture at node N9 in the internal heat exchanger . Therefore, the enthalpy of the state of node N7 is greater than the enthalpy of the state of node N6.

In the refrigeration cycle device 200, the enthalpy of the non-azeotropic refrigerant mixture flowing into the heat exchanger 6 functioning as an evaporator in the heating operation (the enthalpy in the state of the node N2) is the same as the non-azeotropic refrigerant mixture flowing out from the expansion valve 4A. is reduced by the internal heat exchanger 7 than the enthalpy of (the enthalpy of state C2). Further, the enthalpy of the non-azeotropic refrigerant mixture sucked into the compressor 1 (the enthalpy in the state of node N8) is higher than the enthalpy of the non-azeotropic refrigerant mixture flowing out of the heat exchanger 6 (the enthalpy in the state of node N6). increased by the internal heat exchanger 7; Therefore, the difference between the enthalpy of the non-azeotropic refrigerant mixture flowing into the heat exchanger 6 and the enthalpy of the non-azeotropic refrigerant mixture sucked into the compressor 1 increases. As a result, the efficiency of the heating operation of the refrigeration cycle device 200 can be improved.

FIG. 19 is a flow chart for explaining an example of control of the expansion valve 4C performed by the control device of FIGS. 11 and 17. FIG. The process shown in FIG. 19 is called at regular time intervals by a main routine (not shown) that comprehensively controls the refrigeration cycle apparatus 200 . The processing shown in FIG. 19 is performed in cooling operation and heating operation.

As shown in FIG. 19, the controller 10 determines in S201 whether the expansion valve 4C is open. If the expansion valve 4C is closed (NO in S201), the controller 10 advances the process to S202. In S202, control device 10 determines whether or not the difference (temperature gradient) between temperatures T91 and T92 is equal to or greater than threshold value δ1. If the temperature gradient is smaller than threshold value δ1 (NO in S202), control device 10 returns the process to the main routine. If the temperature gradient is greater than or equal to threshold value δ1 (YES in S202), control device 10 advances the process to S203. In S203, the controller 10 opens the opening of the expansion valve 4C by the reference opening and returns the process to the main routine.

If the expansion valve 4C is open (YES in S201), the controller 10 advances the process to S204. Control device 10 determines in S204 whether or not the difference between temperatures T91 and T93 is equal to or greater than threshold value δ2. If the difference between temperatures T91 and T93 is smaller than threshold value δ2 (NO in S204), control device 10 advances the process to S205. After reducing the opening of the expansion valve 4C by a constant opening in S205, the control device 10 returns the process to the main routine. If the difference between temperatures T91 and T93 is equal to or greater than threshold value δ2 (YES in S204), control device 10 proceeds to S206. After increasing the opening of the expansion valve 4C by a constant opening in S206, the controller 10 returns the process to the main routine.

By controlling the expansion valve 4C as shown in FIG. 19, the temperature gradient in the evaporator is reduced and local frost formation is suppressed, so the frequency of defrosting operation can be reduced. Therefore, deterioration of the performance of the refrigeration cycle device is suppressed. Since the priority of control is related to product reliability, the processing of the flowchart of FIG. 20 shown below has priority over that of FIG.

FIG. 20 is a flowchart for explaining the control of the flow rate adjustment valve that is executed during operation in the third embodiment. The processing shown in FIG. 20 is called at regular time intervals by a main routine (not shown) that comprehensively controls the refrigeration cycle apparatus 200 . First, in S31, the control device 10 calculates pressure threshold values Pth1 and Pth2 based on the discharge temperature Td. Calculation of pressure threshold values Pth1 and Pth2 is the same as in the first and second embodiments, and thus description thereof will not be repeated.

Subsequently, in S32, the control device 10 determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1.

If Pd<Pth1 does not hold (NO in S32), in S33, the control device 10 decreases the opening degree B of the expansion valve 4C by the first set amount Δβ1. As a result, of the refrigerant sucked into the compressor 1, the amount of refrigerant with a high HFO1123 concentration that has been sucked into the compressor 1 from the vicinity of the refrigerant liquid surface of the receiver 5 via the evaporator is reduced. Then, the map that defines the threshold value Pth1 shown in FIG. 3 shifts in the direction of the arrow in FIG. 3, so that if the temperature Td remains the same, the pressure threshold value Pth1 increases. The relationship between such a change in threshold value and the degree of opening B of the expansion valve 4C is obtained experimentally in advance and stored in the memory of the controller 10. FIG. Therefore, in S33, control device 10 decreases opening degree B of expansion valve 4C and increases pressure threshold value Pth1. That is, the boundary line BD1 in FIG. 3 is moved according to the opening degree B.

Thereafter, in S34, the controller 10 determines whether or not the expansion valve 4C is fully closed. If not (NO in S34), the pressure threshold values Pth1, Pth2 is calculated.

If the opening of the expansion valve 4C is fully closed (YES in S34), the concentration of HFO 1123 sucked into the compressor 1 cannot be reduced even if the expansion valve 4C is operated any further. Therefore, in S35, the control device 10 again determines whether or not the discharge pressure Pd is lower than the pressure threshold value Pth1. NO at S36, the frequency of the compressor 1 is lowered or the air volume of the condenser fan is increased to lower the discharge pressure Pd, and the determination of S35 is performed again. Note that the compression ratio can be further reduced by further increasing the air volume of the fan of the evaporator, which is more preferable for reducing the discharge temperature. Further, if the fan air volume cannot be increased according to the user setting when the indoor unit becomes the condenser during heating operation, only the air volume of the outdoor unit (evaporator) fan may be increased.

If Pd<Pth1 is established in S32 or S35 (YES in S32 or YES in S35), control device 10 determines in S37 whether discharge pressure Pd is greater than pressure threshold value Pth2.

If Pd>Pth2 does not hold (NO in S37), in S38 the control device 10 increases the opening degree B of the expansion valve 4C by the second set amount Δβ2. As a result, of the refrigerant sucked into the compressor 1, the amount of refrigerant with a high concentration of HFO1123 that has been sucked into the compressor 1 from the vicinity of the refrigerant liquid surface of the receiver 5 via the evaporator increases. Then, the map that defines the threshold values Pth1 and Pth2 shown in FIG. 3 shifts in the direction opposite to the arrow in FIG. . The relationship between such a change in threshold value and the degree of opening B of the expansion valve 4C is obtained experimentally in advance and stored in the memory of the controller 10. FIG. Therefore, in S38, control device 10 increases opening degree B of expansion valve 4C and decreases pressure threshold values Pth1 and Pth2. That is, the boundary lines BD1 and BD2 in FIG. As a result, the pressure threshold values Pth1 and Pth2 that are recalculated in S31 after that are lower than the present values.

If Pd>Pth2 is established (YES in S37), the adjustment of the expansion valve 4C is completed, and the control is once returned to the main routine.

By controlling the expansion valve 4C as shown in FIG. 20, the disproportionation reaction can be reliably suppressed, and the ratio of HFO 1123 can be increased. Frost formation is suppressed, and the frequency of defrosting operation can be lowered. Therefore, deterioration of the performance of the refrigeration cycle device is suppressed.

As described above, in the refrigeration cycle apparatus of Embodiment 3, when the non-azeotropic refrigerant mixture sucked into the compressor 1 is likely to undergo a disproportionation reaction, the refrigerant delivered from the receiver 5 Lowering the concentration of HFO1123 widens the region where the disproportionation reaction occurs. Also, when suppressing the disproportionation reaction with CF3I, the weight ratio of CFI3 and R32 is controlled to such an extent that a temperature gradient does not occur in the evaporator of the non-azeotropic mixed refrigerant.

In this way, it is possible to reduce the GWP of the non-azeotropic refrigerant mixture while suppressing deterioration in the performance of the refrigeration cycle device using the non-azeotropic refrigerant mixture.

Embodiment 4.
FIG. 21 is a functional block diagram showing the configuration of a refrigeration cycle device 200A according to Embodiment 4. As shown in FIG. As shown in FIG. 21 , the refrigeration cycle device 200A includes an outdoor unit 210A and an indoor unit 120. As shown in FIG. Indoor unit 120 has the same configuration as that of the first embodiment shown in FIG. 1, and therefore description thereof will not be repeated.

The outdoor unit 210A differs from the configuration of the outdoor unit 210 shown in FIG. The configuration of other parts of outdoor unit 210A is the same as the configuration of outdoor unit 210, so description thereof will not be repeated.

In the fourth embodiment, unlike the third embodiment, the temperature gradient in the evaporator cannot be adjusted, but by performing the processing of the flowchart shown in FIG. It is possible to adjust the weight ratio of HFO1123. Therefore, it is possible to expand the operating range while suppressing the disproportionation reaction of the refrigerant.

(summary)
The present disclosure relates to a refrigeration cycle device in which a non-azeotropic refrigerant mixture is used in a refrigerant circuit. A refrigerant circuit of the refrigeration cycle device 100 includes a compressor 1, a condenser, an expansion valve LEV1, and an evaporator. The non-azeotropic refrigerant mixture circulates through the compressor 1, the condenser, the expansion valve LEV1, and the evaporator in order in the refrigerant circuit. The non-azeotropic refrigerant mixture contains at least R32, CF3I, and HFO1123. The weight ratio of R32, the weight ratio of CF3I, and the weight ratio of HFO1123 in the non-azeotropic mixed refrigerant enclosed in the refrigeration cycle device are represented by W(R32), W(CF3I), and W(HFO1123), respectively. and W(R32) is 43 wt% or less, W(HFO1123) is 14 wt% or more and less than 70 wt%, and W(CF3I) is more than 2 wt% and W(R32) or less.

Preferably, as shown in FIG. 14, R1234yf is mixed in the non-azeotropic mixed refrigerant so that the total mixing ratio of R32 and R1234yf is 13 wt % or less. The temperature gradient can be made equal to or less than that when CF3I is mixed by setting the mixing ratio to the above-mentioned ratio or less.

Preferably, as shown in FIG. 15, R1234ze(E) is mixed in the non-azeotropic mixed refrigerant so that the total mixing ratio of R32 and R1234yf is 3.8 wt % or less. The temperature gradient can be made equal to or less than that when CF3I is mixed by setting the mixture ratio to the above-mentioned ratio or less.

Preferably, as shown in FIGS. 1, 6, 7, and 8, the refrigerating cycle device has an air gap between the suction portion of the compressor 1 and a liquid reservoir portion in which the non-azeotropic mixed refrigerant liquid refrigerant accumulates in the refrigerant circuit. Bypass paths BL, BL1, and BL2 communicating with each other, flow control valves LEV2, LEV2-1, and LEV2-2 provided in the bypass paths BL, BL1, and BL2, and a temperature sensor 13T for detecting the discharge temperature of the compressor 1 , a pressure sensor 13P for detecting the discharge pressure of the compressor 1, and a control device 10 for controlling the flow control valves LEV2, LEV2-1, LEV2-2 based on the outputs of the temperature sensor 13T and the pressure sensor 13P. The controller 10 adjusts the flow rates of the compressor 1 and the flow control valves LEV2, LEV2-1, and LEV2-2 so that the discharge temperature is equal to or lower than the temperature threshold value τ1 and the discharge pressure is equal to or lower than the pressure threshold value Pth1. adjust. The pressure threshold is a pressure indicating boundaries BD1, BD2, and BD3 of disproportionation reaction regions of the non-azeotropic mixed refrigerant predetermined corresponding to W(HFO1123) and discharge temperature Td as shown in FIG. be.

More preferably, as shown in FIG. 3, the pressure threshold value Pth1 is represented by the following formula (1) on the xy plane where the y-axis is temperature and the x-axis is pressure.
y=0.0005955741x ⁶ -0.0335925804x ⁵ +0.7640964499x ⁴ -9.0197555118x ³ +59.8464849395x ² -232.4345022252x+537.6463398423 (1)
More preferably, as shown in FIGS. 1 and 9, the bypass path provided in the liquid pool portion (accumulator ACC or condenser) is installed at the lowest position of the liquid pool portion in the direction of gravity. It is

Preferably, as shown in FIG. 11, the refrigerant circuit further includes a receiver 5 that stores surplus refrigerant. The non-azeotropic refrigerant mixture circulates through the compressor 1, the condenser, the receiver 5, and the evaporator in order in the refrigerant circuit. The refrigeration cycle device includes a bypass passage (N9) that communicates between the portion of the receiver 5 in which the gas refrigerant of the non-azeotropic refrigerant mixture is accumulated and the suction portion of the compressor 1 or the refrigerant inlet portion of the evaporator, and a bypass passage (N9) provided in the bypass passage. and a cooling device (internal heat exchanger 7) provided in the bypass path for cooling and liquefying the gas refrigerant passing through the bypass path.

More preferably, as shown in FIGS. 11 and 17, the refrigeration cycle device 200 includes a first temperature sensor 9A provided in a portion of the receiver 5 where gas refrigerant is stored, and a portion of the receiver 5 where liquid refrigerant is stored. A second temperature sensor 9B provided in, a third temperature sensor 9C provided between the expansion valve 4c and the internal heat exchanger 7, a first temperature sensor 9A and a second temperature sensor 9B, a third temperature sensor 9C further includes a control device 10 for controlling the expansion valve 4C based on the output of . As shown in FIG. 19, the control device 10 determines that the difference between the temperature T91 detected by the first temperature sensor 9A and the temperature T92 detected by the second temperature sensor 9B and the difference between the temperatures T91 and T93 are predetermined temperature differences. The flow rate of the refrigerant passing through the expansion valve 4C is adjusted so that

More preferably, refrigeration cycle apparatus 200 further includes a third temperature sensor 13T that detects the discharge temperature of compressor 1 and a pressure sensor 13P that detects the discharge pressure of compressor 1 . The control device 10 adjusts the flow rate of the expansion valve 4C so that the discharge temperature Td is equal to or lower than the temperature threshold value τ1 and the discharge pressure Pd is equal to or lower than the pressure threshold value Pth1. As shown in FIG. 3, the pressure threshold value Pth1 indicates boundaries BD1, BD2, and BD3 of disproportionation reaction occurrence regions of the non-azeotropic refrigerant mixture predetermined corresponding to W(HFO1123) and the discharge temperature Td. pressure.

Preferably, the refrigerating cycle device 100, as shown in FIG. and an intermediate temperature sensor 17 . Before and after starting the compressor 1, the amount of increase in the temperature Tm6 detected by the first intermediate temperature sensor 14 is greater than or equal to the first temperature threshold value ΔT1, and the amount of decrease in the temperature Tm3 detected by the second intermediate temperature sensor 17 is , the second temperature threshold ΔT2 or higher, the compressor 1 continues to operate. On the other hand, before and after the start of the compressor 1, the increase width of the temperature Tm6 detected by the first intermediate temperature sensor 14 is less than the first temperature threshold value ΔT1, or the temperature Tm3 detected by the second intermediate temperature sensor 17 If the width of the decrease is less than the second temperature threshold ΔT2, the compressor 1 stops operating.

It is also planned that each embodiment and each modified example disclosed this time will be combined as appropriate within a non-contradictory range. It should be considered that the embodiments and modifications disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all changes within the meaning and scope equivalent to the scope of the claims.

1 compressor, 2 four-way valve, 3, 6 heat exchanger, 4A, 4B, 4C, LEV1 expansion valve, 5 receiver, 7 internal heat exchanger, 8 three-way valve, 9A, 9B, 9C, 13, 13T, 14, 15, 16, 17 temperature sensor, 10 control device, 11 outdoor fan, 12 indoor fan, 13P pressure sensor, 100, 100A, 200, 200A refrigerating cycle device, 110, 110A, 210, 210A outdoor unit, 120 indoor unit, BL1 1st bypass flow path, BL2 2nd bypass flow path, FP1, FP2 flow path, LEV2 flow control valve.

Claims (6)

A refrigeration cycle device in which a non-azeotropic mixed refrigerant is used in a refrigerant circuit,
The refrigerant circuit is
a compressor;
a condenser;
an expansion mechanism;
and an evaporator,
The non-azeotropic refrigerant mixture circulates in the order of the compressor, the condenser, the expansion mechanism, and the evaporator in the refrigerant circuit,
The non-azeotropic refrigerant mixture contains R32, CF3I, and HFO1123,
W (R32), W (CF3I), W (HFO1123),
W (R32) is 43 wt% or less,
W (HFO1123) is 14 wt% or more and less than 70 wt%,
W(CF3I) is greater than 2 wt% and less than or equal to W(R32) ;
The refrigeration cycle device is
a bypass passage that communicates between a suction portion of the compressor and a liquid reservoir portion in which the liquid refrigerant of the non-azeotropic refrigerant mixture accumulates in the refrigerant circuit;
a flow control valve provided in the bypass route;
a temperature sensor that detects the discharge temperature of the compressor;
a pressure sensor that detects the discharge pressure of the compressor;
a control device that controls the flow rate adjustment valve based on the outputs of the temperature sensor and the pressure sensor;
The control device adjusts flow rates of the compressor and the flow control valve so that the discharge temperature is equal to or lower than a temperature threshold and the discharge pressure is equal to or lower than a pressure threshold;
The refrigeration cycle apparatus, wherein the pressure threshold value is a pressure indicating a boundary of a region in which a disproportionation reaction occurs in the non-azeotropic refrigerant mixture, which is predetermined corresponding to W(HFO1123) and the discharge temperature. 2. The refrigeration cycle apparatus according to claim 1, wherein R1234yf is mixed in said non-azeotropic mixed refrigerant so that the total mixing ratio of R32 and R1234yf is 13 wt % or less. 2. The refrigeration cycle apparatus according to claim 1, wherein the non-azeotropic refrigerant mixture contains R1234ze( E) such that the total mixing ratio of R32 and R1234ze(E) is 3.8 wt % or less. . In the xy plane, where the y-axis is temperature and the x-axis is pressure, the pressure threshold is:
y=0.0005955741x ⁶ -0.0335925804x ⁵ +0.7640964499x ⁴ -9.0197555118x ³ +59.8464849395x ² -232.4345022252x+537.6463398423
The refrigeration cycle apparatus according to claim 1, represented by. 2. The refrigerating cycle apparatus according to claim 1, wherein a mounting position of said bypass provided in said liquid pool portion is provided at a lowermost position of said liquid pool portion in the gravitational direction. a first intermediate temperature sensor installed in an intermediate portion of the refrigerant flow path of the condenser;
a second intermediate temperature sensor installed in an intermediate portion of the refrigerant flow path of the evaporator;
Before and after the compressor is started, the range of increase in the temperature detected by the first intermediate temperature sensor is equal to or greater than a first temperature threshold, and the range of decrease in the temperature detected by the second intermediate temperature sensor is equal to or greater than the second above the temperature threshold, the compressor continues to run;
before and after the compressor is started, the increase width of the temperature detected by the first intermediate temperature sensor is less than the first temperature threshold value, or the decrease width of the temperature detected by the second intermediate temperature sensor is The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein the compressor stops operating when the temperature is less than the second temperature threshold.

Images